
Book 'lis 



U. S. COMMISSION OF FISH AND FISHERIES. 
GEORGE M. BOWERS, Commissioner. 



ARTIFICIAL PROPAGATION 



OF THE r 



ATLANTIC SALMON, RAINBOW TROUT, 



AND 



BROOK TROUT. 



Extracted from the Revised Edition of the Fish Maanal. Pages 17 to 90, Plates 11 to 29. 



WASHINGTON: 

GOVERNMENT PRINTING OFFICE.. 
1900. 



U. S. COMMISSION OF FISH AND FISHERIES. 
GEOBGE M. BOWERS, Commissioner. 



\ ; 



ARTIFICIAL PROPAGATION jS2_ 



OF THE 



ATLANTIC SALMON, RAINBOW TROUT, 



AND 



BROOK TROUT. 



Extracted from the Revised Edition of the Fish Mannal. Pages 17 to 90, Plates 11 to 29. 



WASHINGTON: 

GOVERNMENT PRINTING OPFICK, 

1900. 






7 19CS 

D. ot a 



Fish Manual. (To face page 17. 



Plate 1 1, 



fc-v 



#"w 



V-.- \ -■ 4>-%--.i/7-/ 




THE ATLANTIC SALMON 



DESCRIPTION OF THE FISH. 

The body of the Atlantic >s;iliuoii {Salmo salar) is moderately elongate 
and but little compressed; tlie greatest depth is about one-fourth the 
total length without the caudal fin. The length of the head is about 
equal to the body depth. The mouth is of moderate size, the maxillary 
reaching just past the eye, its length contained 2^ or 3 times in the 
head. The scales are comparatively large, becoming embedded in adult 
males; the number in the lateral line is about 120, with 23 above and 
21 below that line. The dorsal fin has 11 rays and the anal 9 rays. The 
pyloric cceca number about C5. 

The color, like the form, varies with sex, age, food, and condition. 
The adult is brownish above and silvery on the sides, with numerous 
small black spots, often x or xx shaped, on the head, body, and fins, 
and with red patches along the sides in the male. Young salmon (parrs) 
have about 11 dusky crossbars, besides black and red spots. 

RANGE. 

The salmon native to the rivers of the northeastern United States is 
specifically identical with the salmon of Europe and all the affluents of 
the North Atlantic. Its original natural range in America appears to 
have been from Labrador or Hudson Bay on the north to the vicinity of 
New York on the south. Within these limits, at the proper season of the 
year, it ascended, for the purpose of reproduction, nearly every river 
except those that did not afford the requisite facilities for depositing 
spawn or were inaccessible by reason of impassable falls near their 
mouths. 

In American rivers frequented by Atlantic salmon they were found 
successively in all ])arts from the mouth upward, their migrations extend- 
ing nearly to the headwaters of all the branches so far as they were 
accessible and adapted to their necessities. The one exception is the 
liver St. Lawrence, where it seems probable, from such evidence as is 
available, that few if any salmon entering the river from the sea ever 
ascended as far as Lake Ontario, and that the salmon inhabiting that lake 
and its tributaries have always, as a rule, made the lake their sea and 
tiie limit of their downward nngrations. Within or partly within the 
limits of the United States there can be enumerated twenty-eight rivers 
that were beyond doubt naturally frequented by salmon, beginning with 

F. M. 3 17 



18 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

the St. John and ending with the Housatouic* In the greater part 
of these the species has been exterminated by civilized man, and in 
the few in which it still persists its numbers are far below the estimates 
which the earliest records warrant us in making for those days. 

In certain lakes of Maine and northward this fish is perfectly land- 
locked and has somewhat difiereut habits and coloration, but no distinct 
specific characters. Similar landlocked varieties occur in Europe. 

LIFE AND HABITS. 

Salmon eggs are deposited od coarse gravel on some rapid, generally 
far lip toward the sources of a river, late in October or early in Novem- 
ber, when the water is perhaps about 44^" F. and the temperature is 
talliug. The egg is impregnated at the moment of its deposit, and the 
iiidei)endent life of the salmon begins to develop at once. In a few 
weeks the embryo becomes sensitive, but the extreme cold of the water 
retards its development to sucli an extent that it does not burst the 
shell of the egg until spring. In the rivers of New England it is i)rob- 
able that nearly all tlie eggs naturally deposited hatch very late in 
Ai^ril and early in May. At this time the embryo salmon has a slender 
half- transparent trunk, less than an inch in length, carrying, suspended 
beneath, an immense ovoid sac — the " yolk-sac." For about six weeks 
after hatching it hides in crevices among stones, keeping up an inces- 
sant fanning with its pectoral fins. During this period it takes no food, 
but is supported and nourished by the yolk-sac, the substance of which 
is gradually absorbed into the rest of the body, and not until the sac 
has nearly disappeared does the salmon really look like a fish and begin 
to seize and swallow food. It now i)uts on a mottled coat, with several 
heavy dark bars across its sides, and bright red spots, larger and fewer 
than those of a trout, looking therefore very unlike the adult salmon 
but much like a young trout. In this stage it is termed, in Scotland 
and England, a "parr," and it was formerly thought to be a wholly 
different species from salmon. 

The parr stage lasts a year or two in British rivers, and the few 
observations made in America indicate that it is more likely two years 
than one in our rivers. The parr, at first but little over an inch in 
length, is provided with good teeth and a good appetite, and beginning 
to feed at a season of the year when the water is almost crowded with 
small insects and other more minute creatures, it grows rapidly, prob- 
ably increasing its weight thirty or forty times the first summer. In 
two years it reaches the length of 6 or 8 inches, and its bright red 
spots and dark bars have given place to a silvery coat like the adult 
salmon. It is now termed a "smolt" and is ready to go to sea, which 
it does with little delay, and passes out beyond the range of man's 



■*Tlie Hudson River is ]>\ some helioved to have been a natural salmon river. Its 
discoverer, liciidrik HikIsou, reported having observed them there, and there ia 
uutbini; inherently improlta.M.e iu it, but the evidence is perhaps iusufficieut. 



MANUAL OF FISH-CULTURE. 19 

observatiou, but to a regiou where it finds a rich feeding- ground and 
rapidly increases in size.* In northern rivers, tliose of New Brunswick 
and beyond, as in those of northern Europe, the salmon returns from 
the sea when it has attained a weight of 2 to 6 pounds, and is then 
termed a "grilse." 

In the rivers of Canada, in general, grilse occur in great numbers, 
coming in from the sea at a later date than the adults, but ascending 
like them to the upper waters, mingling freely with them, rising to the 
same fly, and caught in the same weirs. The mesh of the nets is limited 
by law to a size that takes the adult salmon, but allows the grilse to 
slip through. To this circumstance it is in part owing that by the 
time the fish have reached those portions of the rivers suitable for 
angling there is commonly, if it be late enough in the season, a great 
preponderance of grilse, so that more of the latter than of the former 
are taken by the angler. In Nova Scotia many grilse are taken in the 
Shubenacadie River from August until late in the fall. On the Mirami- 
chi, in New Brunswick, grilse make their appearance about July 1, and 
from the middle of that month till the end of Angust they constitute 
the main body of the salmon entering the river. Some sportsmen 
report that the grilse caught exceed the adults in the ratio of 5 to 1. 

In the month of August, in the Nepissiguit, Restigouche, and St. 
John of Gaspe, grilse have been found in some years to exceed the 
adults in the ratio of 3 to 1. They run into the Nepissiguit mostly 
between July 25 and September I. Their scarcity during theearly part 
of the angling season, or say previous to July 20, is attested by numer- 
ous fishing scores. A series of scores of salmon fishing in the Godbout 
River, on the north side of the St. Lawrence, shows that ])revious to 
July 15 or 20 the adult salmon taken with the fly in that river exceed 
the grilse in the ratio of 10 to 1 or more. 

In our rivers grilse are seldom seen, and only 3 or 4 are taken per year 
in a weir in the St. Croix, which takes about 70 adults. In the Dennys 
River the ratio of grilse to salmon caught is not more than 1 to500, and 
in the Penobscot they are quite as rare. Adult salmon running in this 
river several weeks earlier than in those of eastern New Brunswick, we 

* There lias been considerable discussion on this point, and the conclusions of some 
observers nrv, at variance with the above statement. Li Scotland many years ago it 
seemed to be well established by the observations of Bnist that a portion of the young 
salmon put ou the silvery coat and went to sea at the age of one year, but that oth(Ms 
of the same brood did not get ready to go until two years old. American observa- 
tions, however, tend strongly to the conclusion that the young salmon passes two 
whole summers in the river, going out to sea in the autumn following its seco id 
Slimmer or the nest spring. It is not probable that the seaward migration is 
restricted in any river to any exact jieriod of a few weeks duration, but that it 
extends over many mouths, some of the young salmon, l)y reason of superior native 
vigor of growth or from other equally efficient cause, attaining the migratory stage 
montlis earlier than others of the same brood. 

It is the opinion of one American ol)server that salmon fry remain in the streams 
until October of the second year before going to se.n. and that they do not go down 
until the spring of the third year; i. e., when they are two years old; though some 
may go down f h(>, fall of the second year; and that the salmon do not return until 
they arc four years old. 



20 REPOBT OF COMMISSIONER OF FISH AND FISHERIES. 

should naturally exi)ect the advent of grilse early in July in considerable 
numbers ; but some of the weirs are often kept in operation until the 
middle or last of July, and sometimes even through August, when they 
take menhaden ; but no grilse enter them. During the latter part of the 
summer the water at the several falls between Bangor and Oldtown is 
generally at a low stage, and the attempt of grilse, even in small num- 
bers, to ascend the river could hardly fail to be frequently detected. 
A similar state of things exists in the Kennebec. There is no escaping 
the conclusion that the great run of grilse, which is so prominent a fea- 
ture in the history of the salmon of northern rivers, is almost entirely 
wanting in the rivers of the United States. It by no means follows from 
this that our salmon do not pass through the same phases of growth, or 
that the growth is more rapid, but merely that when in the grilse stage 
they generally lack the instinct that impels their more northern relatives 
to seek fresh water. 

Of the characteristics of grilse, as ascertained in the rivers they 
frequent, it will be sufiQcient to say that they exhibit to a great degree 
the characteristics of the adult; that the main external differences 
are a shorter head, slenderer form, and a difference in the color and 
markings; that they are remarkably active and agile, leaping to great 
heights; that the mule is sexually well developed and mates with the 
adult, but that the female is immature, and that, like the adult, they 
abstain from food and consequently lose flesh during their stay in fresh 
water. 

The next stage of life of the fish is that of the adult salmon, and this 
is the stage at which, with the exceptions indicated above, the Atlantic 
salmon first ascends the rivers of the United States. Assuming that it 
relinquished the rivers for the sea at the age of two years, being then 
asmolt, it has been absent two years, and it is now four years or a little 
more since it burst the shell. This estimate of age is based on the 
observations made by the Massachusetts commissioners of fisheries 
on the return of salmon to the Merrimac River, which plainly estab 
lished the fact that the entire period between the hatching of the fry 
and the return of the adult to the rivers is about four years. Whether 
the same rule holds in other New Eiigiaiid rivers can not as yet be 
established, owing to deficient data, but the presumption is in t^vor of 
that conclusion. In Canadian rivers the same period of growth appears 
to be the universal rule, at least as far north as the St. Lawrence River. 
Statistics of the catch of salmon for many years in eighteen separate 
districts, showing many fluctuations, exhibit a remarkable tendency of 
the figures to arrange themselves in periods of five years; thus, tlic 
year 3875 having been a year of small catch of salmon, it also appears 
in most of the districts that the next year of abnormally small catcii 
was 1880. Now, the eggs laid in 1875 would hatch in 1870, and the 
young hatched at that time would be grown m 1880, requiring thus 
four years from hatching to maturity, just ns on the Meirimac. It 
would seem uo other interpretation can be put upon the statistics. 



Fish Manual. (To face page 20.) 



Plate 12. 




ENTRANCE TO DEAD BROOK INCLOSURE FOR SALMON. 




DEAD BROOK INCLOSURE FOR ATLANTIC SALMON, SHOWING PENS. 



MANUAL OP FISH -CULTURE. 21 

EARLY SALMON-CULTURE ON THE PENOBSCOT RIVER. 

The movemeut for the reestablishment of the fisheries for salmon, 
shad, and other anadromous species in American rivers originated in 
the action of the legislatures of New Hampshire and Massachusetts, 
having iu view primarily the fisheries of the Merrimac and Connecti- 
cut rivers. The course of the Connecticut lies partly in the State of 
Connecticut, while many of its tributaries are in the State of Vermont, 
and these two States were therefore early interested in the project, and 
their action soon led to a similar movement on the part of Ehode Island 
and Maine. The rivers within the borders of these six States are the 
only ones in the United States known to have been frequented by the 
seagoing Salmo salar, excei)t possibly the Hudson and certain rivers 
tributary to the St. Lawrence, in the northern part of New York. 

The commissioners to whom the governments of the above States 
confided the task of restocking the exhausted rivers turned theii' 
attention at once to the two most important of the migratory fishes, the 
salmon and the shad. The utter extermination of salmon from most 
of the rivers compelling the commissioners to consider the best mode of 
introducin'g them from abroad, eggs were obtained for a time from the 
spawning-beds in the rivers of Canada and hatched with a measure of 
success. After a few seasons permits for such operations were discon- 
tinued, and it became essential to look elsewhere for a supply of salmon 
ova. In 1870 attention was directed to the Penobscot Eiver, in the 
State of Maine, which, though very unproductive compared with Cana- 
dian rivers, might yet, perhaps, be made to yield the requisite quantity 
of spawn. The fisheries are all in the lower part of the river and in 
the estuary into which it empties, Penobscot Bay, and there the supply 
of adult salmon could be found with certainty, but they must be obtained 
from the ordinary salmon fisheries iu June and held in durance until 
October or November, and the possibility of confining them without 
interfering seriously with the normal action of their reproductive func 
tious was not yet established. 

This plan was finally adopted, and in 1871 this method of breeding 
salmon was first attempted. For the purpose of the experiment, a 
point at the mouth of Craig Brook, which is by water nearly 9 miles 
distant from the mouth of the Penobscot River, more than half the 
route being through brackish water, was selected as the most conven- 
ient fresh- water stream which offered facilities for confining the salmon 
and maturing their eggs. After some unsuccessful trials means were 
found of safely conveying a few live salmon in floating cars from the 
fishing-grounds to the station, where they were held till the spawning 
season, when their eggs were taken and impregnated. ■ 

From 1872 to 187G operations were conducted on a larger scale, with 
a fair degree of success, and, after a suspension, were resumed in 1879 
at Craig Brook hatchery, while the retaining inclosures were located 
in Dead Brook, about 2 miles distant. The disadvantage of this 



22 REPORT OF COMMISSIONER OP FISH AND FISHERIES. 

distance between tlie batcbery and retaining-ponds was oftset b}^ other 
advautag^eous conditions. 

Until 1880 no attem))t was made to rear sabnon, and with unimpor- 
tant exceptions the work was confined to the collection of salmon eggs, 
their development during the earlier stages, and their transfer in winter 
to other stations to be hatched. In 1889, however, the United States 
Fish Commissioner decided to establish a permanent station at Craig 
Brook, and in anticipation of the ])urcbase of the premises, which was 
concluded the following year, the rearing of salmon to the age of six or 
seven mouths was undertaken as the leading work of the station. 

WATER FOR A SALMON HATCHERY. 

The first requisite for a salmon hatchery is an ample supply of suit- 
able water, on a site where it can be brought (lompletely under control 
and the requisite fall secured. In this matter there is quite a range of 
choice. The very best is the water from a stream fed by a clean lake of 
considerable depth., taken a short distance below the outlet of the lake, 
with an intervening rapid. Craig Pond maybe taken as an example of 
such a lake. It has an area of 231 acres, an extreme dei)th of 69 feet, 
and a depth of 25 feet within 500 feet of the outlet. The depth directly 
influences the temperature and, other things being equal, a deep lake 
will atfonl water more uniform in temperature than a shallow one — cooler 
in summer and warmer, though never too warm, in winter. Such water 
is commonly quite even in volume and temperatuie, andcom]>aratively 
pure. It is cold in winter and warms up slowly in spring, assuring a 
slow, normal development of the eggs, which is more conducive to 
health and vigor than a quicker development. The passage down a 
rapid will further improve this water by charging it highly with air. 

After this, the water of a brook is to be chosen that is fed largely by 
springs, so as to insure constancy in the supply and some moderation 
of the temperature on warm days, but it is better to have the water 
flow a long distance in an open channel before using, and, if possible, 
over a rough and descending bed, that it may be well aerated, and in 
cold weather somewhat cooled down from the temperature with which 
it springs from the ground. 

The next best is pure spring water; but in all cases where this is 
used a cooling and aerating pond is necessary, that the original warmth 
of the- water may be subdued by the cold of the air before it reaches 
the hatching-troughs, and that it may absorb more or less air by its 
wide surface. 

Lastly, choose ordinary river or brook water, as clean as possible. 
These are inferior to spring water by reason of liability to floods, 
drought, muddiness, and foulness of other sorts, and in cold climates 
to anchor ice. 

Between these different sorts there is of course an infinite number of 
gradations. If lake water can not be obtained it would be of some 



Fish Manual. (To face page 22.) 



Plate 13. 




SALMON LIVE-CAR USED IN TRANSPORTING FISH FROM WEIRS TO DEAD BROOK. 




SALMON LIVE-CARS EN ROUTE WITH FISH. 



MANUAL OP FISH-CULTURE. 23 

advantage to have a supply of botli spring Wiiter and brook water, 
depending for ordinary use on the brook water or a mixture of the two, 
and on the spring water for emergencies, such as the freezing, drying, 
or excessive heating of the brook, floods with accompanying muddiness, 
etc. Water coming from boggy and stagnant ponds and marshes is 
objectionable; for though excellent water, capable of bringing out the 
most vigorous of fish, may sometimes be had in such jjlaces, yet when 
not supplied by springs it is dependent for its freshness and good qual- 
ities on rainfalls, and if these fail, as they are liable to, the water may 
become foul and unfit. It must be borne in mind that these remarks 
about the selection of water for fish-cultural purposes apply only to the 
culture of Atlantic or landlocked salmon, in a climate like that of the 
State of Maine. 

It is best to select a site for a hatching establishment in time of 
extreme drought, and if it then has an ample supply of ])ure, sweet 
water the first requisites are fulfilled. It is well also to visit the place 
in time of flood and, if in a cold climate, in severe winter weather, 
to learn the dangers to be guarded against on those scores. The 
volume of water necessary will depend mainly on the proposed capiicity 
of the establishment, the temperature of the water, its character as to 
aeration, and the facilities existing for the aeration and repeated use 
of the water. With water of the highest quality and low temi)erature, 
and with unlimited facilities for aeration, possibly a gallon a minute, 
or even less, can be made to answer for the incubation of 100,000 eggs 
of salmon. As the temperature rises or the facilities for aeration are 
curtailed a larger volume becomes necessary. In case of spring water, 
cooled only to 40° and aerated only by exposure to air in a pool of about 
a square rod surface, with no facilities in the house for aeration, and 
with the eggs and fry crowded in the troughs at the rate of 4,000 per 
square foot, 4 gallons a minute is the least that can be allowed, while 
6, 8, or 10 gallons per minute are better. While the minimum is, as 
stated above, possibly less than a gallon a minute, it is not advisable 
to trust to less than 3 gallons per minute for each 100,000 eggs under 
the most favorable circumstances. 

If the water supply is drawn from a small brook or spring, it is neces- 
sary to measure the volume approximately, which is easily done, in the 
following manner: With a wide board 1 inch thick, lia\ing a smooth 
inch hole bored through the middle, a tight dam is made across the 
stream so that all the water will have to flow through the hole. If the 
water on the upper side rises just to the top of the hole, it indicates a 
volume of 2.3 gallons per minute; a rise of half an inch above the top 
of the hole indicates a volume of 3.5 gallons per minute; 2 inches rise, 5 
gallons per minute; 3 inches, 6 gallons per minute; C inches, 8 gallons 
per minute; 13 inches, 12 gallons per minute. If two l-inch holes are 
bored, the same will, of course, indicate twice the volume. The volume 
of water flowing through holes of different sizes is in proportion to the 



24 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

squares of their diameters ; tlius a 2-iiich hole permits the i)assage of 
four times as much as a 1-iuch hole. A tube whose length is three 
times its diameter will allow 2!) per cent more water to i)ass than a hole 
of the same diameter through a thiu plate or board. 

SITE. 

After a satisfactory supply of water is found a site for the hatching- 
house must be selected that aifords facilities for creating a head of 
water to provide for the requisite fall into and through the troughs, 
security against inundation, security against too mu(;h freezing" if in a 
cold climate, and, liually, general safety and accessibility. The fall 
required in the hatching-house can hardly be too great. The minimum 
is as low as 3 inches, but only under the most favorable circumstances 
in other respects will this answer, and even then it is only admissible 
where there is an ample suppl}^ of aerated water and the troughs are 
very shoi t and there is absolutely no danger of inundation ; and this 
fall has the disadvantages of the iini»ractical)ility of introducing any 
aerating apparatus and the necessity of having the troughs sunk below 
the floor of the hatching-house, which makes the work of attending the 
eggs and fish very laborious. 

A fall of 1 foot will do fairly well if there is entire safety from iuuu- 
dation, as this will permit the troughs being placed on the floor, which 
is a better position than below it, though still an inconvenient one, 
and some of the simpler aerating devices can be introduced. Better is 
a fall of 3 feet, and far better a fall of feet. The latter permits the 
placing of the lowest hatching-troughs 2 feet above the floor and leaves 
ample room for complete aeration. The necessities of the case are 
dependent largely upon the volume and character of the water, and 
if there is plenty of it, well aerated before reaching the hatching-house, 
there is no occasion, in a small establishment, of additional aeration in 
the house, and therefore no need of more than 3 feet fall. 

Inspection of the premises at time of floods will suggest the safe- 
guards necessary to provide agai nst inundation. If located by a brook- 
side, the hatching-house should not obtrude too much on the channel, 
and below the house there should be an ample outlet for everything that 
may come. By clearing out and enlarging a natural watercourse much 
can often be done to improve an originally bad site. 

In a cold climate it is an excellent plan to have the hatching-house 
partly under ground, for greater protection against outside cold. When 
spring water is used there is rarely any trouble, even in a cool house, 
irom the formation of ice in the troughs; but water from lake, river, or 
brook is, in the latitude of the northern tier of States, so cold in winter 
that if the air of the hatching-house is allowed to remain much below 
the freezing-point ice will form in the troughs and on the floor to such 
an e:jitent as to bo a serious annoyance, and if not watched will form 
in the hatching-troughs so deeply as to freeze the eggs and destroy 



MANITAI, OF FISH-CULTURE. 25 

them. Stoves are uccded iu such climates to warm the air enongli 
for the comfort of the attendants; but the house thould be so located 
and constructed that it may be left without a fire for weeks without 
any dangerous accumulation of ice, and if the site does not permit of 
building the house partly under ground the walls must be thoroughly 
constructed and banked well with earth, sawdust, or other material. 
In warmer climates no trouble will be experienced from this source. 

DAMS AND CONDUITS. 

The requisite head of water can often be had by throwing a dam 
across the stream and locating the hatching-house close to it. The 
dam will form a small pond which will serve the triple i)urpose of cool- 
ing, aerating, and cleansing the water. But unless the bed and the 
banks of the stream are of such character as to preclude any danger 
of undermining or washing out the ends of the dam, it is best not to 
undertake to raise a great head in this way. With any bottom except 
one of soHd ledge there is always great danger, and to guard against 
it when the dam is more than 2 feet high may be very troublesome. If 
there is a scarcity of water, or if it is desirable, for aerating or other 
purposes, to secure a considerable fall, it is better to construct the dam 
at some distance above the hatching-house, on higher ground, where a 
very low dam will suffice to turn the water into a conduit which will 
lead it into the hatching-house at the desired height. 

A square conduit made of boards or planks, carefully jointed and 
nailed, is in nearly all cases perfectly satisfactory, and for an ordinary 
establishment a very small one will suffice. 

The volume of water that will flow through a i^ipe of a given form 
depends upon its size and the inclination at which it is laid. A straight 
cylindrical pipe, 1 inch in diameter, inclined 1 foot in 10, conveys about 
11 gallons of water per mhiute. The same pipe, with an inclination 
of 1 in 20, conveys 8 gallons per minute; with an in(dination of L in 
100, it conveys 3J gallons per minute; with an inclination of 1 in 1,000, 
it conveys 1 gallon per minute. A 2-inch pipe conveys about 5^ times 
as much water as an inch pipe; a 3-inch pipe nearly 15 times as much. 
A 1-inch pipe, with an inclination of 1 in 1,000, conveys water enough 
for hatching 25,000 eggs; with an inclination of 1 in 50, enough for 
100,000 eggs; with an inclination of 1 in 20, enough for nearly 200,000 
eggs. A square conduit conveys one-quarter more water than a cylin- 
drical pipe of the same diameter. If there are any angles or abrujtt 
bends in the pipe, its capacity will be considerably reduced. It should 
be remembered that if the water completely fills the aqueduct it is 
entirely shut out from contact with the air during its i)assage, whereas 
if the pipe is larger than the water can fill, the remainder of the space 
will be occupied by air, of which the water, rushing down the incline, 
will absorb a considerable volume and be greatly improved. It is 
therefore much better to make the conduit twice or thrice the size 



26 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

deniauded by tlie required volnine of watei'. If tlie bottom and sides 
are rough, so as t<f break up tlio water, so much tbe better, and the 
wider tbe conduit is the more surface does the water present to the air. 

AERATION. 

The water wliich fishes breathe is but tlie niedir.m loi' the conveyance 
of air, which is the real vivilyiiig agent, without which fish and eggs 
will die, and with a scanty su])ply of which the ]>roper development of 
the growing enibryo is imiJO.-sible. Water readily absorbs air when- 
ever it comes in < ontact with it, and the more intimate and the longer 
continued the contact the greater the voluiue it will absorb. The ami»ie 
aeration of the water to be used in the hatching-house has already been 
mentioned as a desideratum of the first importance, and some of the 
devices by which it is to be secured have been alluded to. 

Water from either a brook or a river that has been torn into froth by 
dashing down a steep bed has absorbed all the air that is needed in 10 
or 20 feet of hatching-trough, and demands no further attention on this 
score; but if the water is taken from a lake, a spring, or a quiet brook 
it contains less air, which may be so reduced before it gets through the 
hatching-house as to be unable to do its proper work. It is therefore 
desirable to adopt all practicable means of reinforcing it. If the site 
of the hatching-house commands a fall of 5 feet or more, the object 
may be attained by contriving in the conduit outside the house, or in 
the hatching-troughs themselves, a series of miniature cascades. 

The broader and thinner the sheet of water the more thoroughly it is 
exposed to the air, and if, instead of being allowed to trickle down the 
face of a perpendicular board, it is carried off so that it must fall free 
through the air, both surfaces of the sheet are exposed and the effect 
is doubled. When circumstances permit, it is best to aerate in the 
conduit, whi(;h, as already suggested, may be made wide and open for 
that ijurpose. 

If aeration can not be effected outside the house it may be done 
inside by arranging two long troughs side by side, leveled carefully, 
so that the water is received in one of them and poured over into the 
other in a sheet the whole length of the trough. In the hatching- 
troughs themselves there is an opportunity for aeration, either by 
making short troughs with a fall from one to another or by inclining the 
troughs and creating falls at regular distances by partitions or dams, 
each with its cascade, after the fashion already described.' The only 
serious difliculty is encountered where the ground is very flat, so that 
the requisite fall can not be obtained, and in this case the best that 
can be done is to make a very large pool, several square rods at least, 
outside the house, and make all the conduits as wide as possible, so 
tliatthe water shall flow in a wide and shallow stream. 

It will of couise be borne in mind that the better the aeration the 
smaller the voluiue recpiired to do a given work, and on the other hand 



MANUAL OF FISH-CULTURE. 



27 



it is equally true that the greater the volume the less aeration is 
necessary. When so large a volume asG gallons per minute for every 
100,( 00 eggs is at command, a comparatively small amount of aeration 
will answer. But, so far as known, the higher the degree of aeration 
the better the result, without limit, other things being equal, and it is 
therefore advised to make use of all the facilities existing for this 
purpose. 

FILTERING. 



Before the introduction of wire or glass trays for hat(;hing fish eggs 
it was customary to lay them on gravel, and it was then absolutely 
necessary to filter all but the ])urest water. Even ordinary spring 
water deposits a very considerable sediment, whicjh might accumulate 
upon the eggs to such an extent as to deprive them of a change of 




o, conduit from brook. 

b, gate, swingiug on pivot at c, to cliauge 

direction of water. 
(/, direct branch of conduit. 
f, reverse branch of conduit. 
/, /, etc., a single long compartment for untiltered 

water. 
g,ij,etc., compartments occupied by gravel. 



Gravel Filter. , 

/(, a single long ccmipMrliiieut t(ir filtered water. 
i,j, racks to hold gravel in place. 
i is in 5 sections, movable, and can be taken out 
when gravel is to be renewed. 
k, I, sluices near bottom for cleaning out. 
■Ill, wasteway. 
n, aqueduct to hatchery. 



water and smother and destroy them. When, however, eggs are depos- 
ited on trays arranged for a circulation of water beneath, as well as over 
them, as described below, even though their upper sides are covered 
with sediment, they are clean and bright underneath and remain in 
communication with the water beneath the tray, though of course the 
circulation of the water through the tray is not perfect. It is not, 
therefore, deemed necessary to introduce any considerable devices for 
filtering water which is naturally very ])ure, like lake and spring water 
when not subject to intermixture with surface water during rains; but 
where it is necessary to use water subject to constant or occasional 
turbidness some method of filtering is indispensable. 

In the majority of cases at least a portion of the water supply is 
obtained from an open brook, lake, or pond, and measures must be taken 



28 REPORT OF COMMISfilONER OF FISH AND FISHERIES. 

to get rid of the leaves and other coarse rubbish brought down by tlie 
stream or conduit. A great deal of such material is encountered in a 
stream at all seasons of the year, but during the fall and early winter 
it is especially abundant, and to secure entire safety from a stoppage of 
the water, and consequent loss, a screen on a generous scale must be 
provided. 

A description of the means adopted at this station for providing a 
temporary extra water service of several hundred gallons per minute, 
taken from Craig Brook, will serve as an illustration : A tank or vat, 
12 feet square and about 2 feet deei), is built in the bed of tlie brook 
with a tight dam of stones, gravel, loam, and leaves (these to stop 
small leaks) running ashore on either side, so that the entire volume of 
the brook passes over the tank. The bottom and. sides are tight and 
strong, and both bottom and top are inclined about 6 inches down the 
stream. The cover is of spruce lumber sawed 1 J inches square and 
n idled on in the direction of the current, with interstices open half an 
inch ; when in operation the water Alls the tank and runs over the lower 
edge, which is raised enough to maintain a depth of several inches over 
nearly the whole tank. All leaves and other materials floating near the 
surface of the water are carried over, together with most rubbish which 
floats deep. At one of the lower corners of the tank, near tlie bottom, 
is a gate about 15 inches square, which is hung by hinges on its upper 
side. It opens inward, and is closed tightly by the i)ressure of the 
water ; but it can be easily opened by pushing with a pole fr<mi without, 
and then serves as a floodgate, whereby the tank may be thoroughly 
cleaned out. 

At the other lower corner is a conduit, G by 9 inches, which takes 
from this "leaf-screen" a su^jply of water not entiiely free from rubbish, 
but so nearly so that a filter of moderate capacity can cope with what 
remains. A very useful adjunct would be a second horizontal screen 
of similar construction, through which the water that has passed down- 
ward through the first screen, as described, should next pass upward 
through the second; the first screen would remove floating debris, the 
second such as is heavier than water. 

The filter, situated about 70 feet from the leaf-screen, consists of a 
wooden flume, 12 feet loug and 4 feet deep, divided lengthwise into three 
compartments, of which the central contains fine gravel held in place 
by a rack on either hand, of which the interstices are ^ inch wide and 
li inches apart. The water from the leaf screen is introduced into one 
of the lateral compartments, and filters through the gravel into the 
op])osite compartment, from which it is taken by a plank aciueduct, G 
by G inches, to the hatchery. Under the conditions described, and with 
a fall of about 1 foot from supply to dis(;harge, this filter discharges 
over .300 gallons of water per miiuite into the aqueduct — water not abso- 
lutely i)ure, but sufficiently free from coarse dirt for the purpose. 
In many cases, where small (]uantities of water are used, it is custo 



MANUAL OP FISH-CULTUKE. 



29 



mary to tilter tliroug-h flauiiel screens in the hatchery, and such filters 
do very good service. They can be iiitroduc(Ml into the egg-troughs, 
or by running- them lengthwise of a trough a very large volume of 
water can be filtered. 

PLAN. 

xn □ a. 




A — 



c 



c 



iJjtMEitt^SPIttllli'illllltltt l ll ll ll l lllllll l lllS RS^ a 
S m mwMn ^M I la. 



u □ u~ 

SEICTION THROUGH A-B 





Scale of feet. 



Wire Filter. 

A form of filter that has given good satisfaction at the Craig Brook 
station through five years of service consists of a series of graduated 
wire screens, throngh which the water passes upward, first through 
the coarser and then through the finer screens, with provision for the 



30 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

reversal of the curieut for cleaning purposes. By reference to the cut 
on page 29, it will be seeu that t!ie water is brought to the filter through 
a plank condnit, and is admitted to the filter through either of two 
gates that swing on hinges, one for the direct flow and the other for the 
reversal. The direct flow is first into a receiving cluimber, which 
extends under the screens, then upward through the whole series and 
out at the top. overflowing into a catch-trough, from which it is dis- 
tributed as desired. In cleansing, the supply-gate is closed and the 
other one opened, and at the same time the sluice-gate at the bottom is 
opened; the water then flows in fall volume upon the screens and down 
through them, carrying all the intercepted debris into the lower cham- 
ber and out through the sluice gate. 

The wire filter illustrated has to pass some 500 gallons of water per 
minute, and has three screen-boxes, each of which carries 5 to 7 screens 
about 2 feet wide and 4 feet long; the meshes are from 2 inches down 
to ^ inch square, and therefore intercept all coarse debris. 

It is but the work of a few moments to reverse the current and 
thoroughly cleanse the screens; when the autumn leaves are falling 
this must be done several times a day, but at other seasons some days 
elapse between the cleanings. The wire — even galvanized — rusts out 
in two or three years, and lately the coarser screens have been made 
of slender rods of oak, which will undoubtedly prove more durable. 

jS^one of the filters described will intercept the finest sediment, and 
the water is finally i^assed through a capacious wooden reservoir, 30 
feet long, 8 feet wide, and 5^ feet deep, before it reaches the troughs. 
This answers the purpose well for the amount of water supplied by the 
filter last described (about 500 gallons per minute) and is regarded as 
well worth having, though even this will not insure limpidity in the 
water when the brook is swollen by rains. 

It may be mentioned that this reservoir is kept brimful at all times, 
so that all portions of the woodwork, except the railing surrounding it, 
are kept continuously wet and thus insured against decay for a very 
long period of years. 

CRAIG BROOK HATCHERY AND ITS EQUIPMENT. 

The Craig Brook hatchery derives its water supply from the brook, 
which has its source in Craig Pond, but which receives in the lower 
part of its course many copious springs. This spring water has some 
advantages, but i)OSsesses the serious disadvantage of such high tem- 
perature in winter as to unduly hasten the development of the eggs, 
causing them to hatch early and necessitating shipments of eggs in 
December. 

Accordingly, an aqueduct from a point on the brook above the springs 
brings to the hatchery a supply of cold water for winter use, in which 
eggs taken the first of November will not hatch until the following 
April. This is important, as, if the product of the season's hatching 
is to be liberated as fry, the late date of hatching will bring them 
to tiie feeding stage about the time when suitable foo«l abounds in 



Fisn Manual. (To face page 30) 



Plate 14. 




MANUAL OF FISH-CULTURE. 31 

open waters, and if tbey are to be reared it is well to shorten up 
the sac-stage and to have the early feeding stage fall at a date wheu 
the temperature of the water is rapidly rising, which will get the fish 
quickly through that most difficult of all stages of growth. 

The aijueduct is about l,tiO() feet long, with a bore 4A inches, and has 
a nearly uniform descent and total freedom from dei^ressions, and is 
from end to end one single piece of cement concrete. It delivers to the 
hatchery about 100 gallons of water per minute, which is sufficient for 
the development of 4,000,000 eggs, and possibly many more. It was 
built in place around a slightly tapering core, which was drawn forwai d 
as fast as the mortar set, and it has now done good service for seven- 
teen years. By this means the temperature of the hatchery water is 
maintained 3° below that of the brook modified by the springs. During 
the five months from IsTovember 1, 1895, to April 1, 1890, the mean tem- 
perature in the hatchery was 36.65° F. 

COLLECTION OF STOCK SALMON. 

The only salmon fisheries available for the purpose of supplying Craig" 
Brook station with breeding fish are those carried on by weirs about 
the mouth of the Penobscot. Arrangements are made early in the 
season with weir fishermen to save their salmon alive and deliver them 
daily to the collecting agent of the station, who makes the rounds of 
the district about low water with a small steamer, which tows the cars 
containing the fish on the flood-tide to Orland -village, where they are 
passed through the lock about high water and taken by a crew of oars- 
men to the inclosure at Dead Brook. 

In anticipation of this work, the fisherman places the floor of his 
weir a little lower than he would otherwise do, so that at low water the 
salmon may have water to swim in instead of being left high and dry 
by the retreating tide, in case of an accidental delay or failure to visit 
the weir at the usual hour. It is, however, the ordinary practice to 
take the salmon out at each "fish-tide," i. e., low water, and place them 
in a car. Cars enough are stationed among the fishermen to bring" one 
at least in each neighborhood, and in most cases the car is brought 
alongside and the salmon transferred to it directly from the weir, 
though in some cases it is necessary to ])lace the salmon first in a box, 
in which it is carried by a boat to the car. The car employed is made 
from the common dory, divided transversely into three compartments. 
The central one, which is nuich the larger, is occupied by the fish, and 
is smoothly lined with thin boards and covered with a net to prevent 
the fish jumping out or being lost by the car capsizing, which some- 
times occurs, while to guard them from fright and the rays of the sun 
a canvas cover is drawn over all. 

The first cars of this form had iron gratings to separate the central 
from the forward and after compartments, the water being admitted 
through the iorward and discharged through the after compartment, 
but this was objectionable because the salmon were constantly seeking 



32 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

to escape througb the forward grating, and often injured themselves by 
rushing against it. Smootli wooden gratings were after wards used and 
for many years cars were employed in which the compartments were 
separated by tight board partitions, the openings for the circulation of 
water communicating through the sides of the boat directly with the 
fish conii)artment and being, of course, grated. This was a very satis- 
factory Ibrm, but when it was found desirable and practicable to use 
ice in traiis])(>rtation, the forward compartment became the ice-room, 
and it was necessary to perforate the partition again to admit the cold 
water to the hsh. L'inally, stout woolen blanket cloth was substituted 
in the partitions, with eyelet holes to afford passage to the water. 
This is the form now in use, in which tiie water is admitted through 
openings in the sides to the ice-room, from which. it passes through the 
fish room to tlie after room, whence it is discharged. 

The car is ballasted so that the rail is just above water or, in case 
of an unusually large load of fish, a little below it, 2i.ll the openings 
communicating with the outside are controlled by slides, which can be 
closed so as to let the car swim high and light when it is towed empty. 

The boxes used for the transfer of salmon hold about !J0 gallons each, 
and are li feet wide, 2 feet deep, and 3 feet long, with a sliding cover, 
in the center of whicli is an inch auger-hole for ventilation. Such boxes 
were used at Bucksport from 1872 to 1874 to convey the salmon on 
drays from the cars to the inclosure, a distance of a little over a mile; 
six or eight salmon were taken at once, the box being tilled brimful 
of water, which was brackish and generally clear and cool. T|iough the 
largest fish could not lie straight in the box, and the time occupied 
in transit was commonly twenty minutes, they as a rvile arrived at the 
pond iu good condition. 

To avoid injury to the fish in transferring them to the cars, fine dip 
nets, lined with woolen flannel of open texture, are used. The bow on 
which the net is hung is 22 inches iu diameter, and to secure a net of 
ample width three ordinary nets, 3(5 inches in depth, are cut open down 
one side quite to the bottom, and then sewed together, giving thus 
three times the ordinary breadth without increasing the depth. 

The collection of salmon is begnn each season usually from the 2()tli 
of May to the 1st of June, but as the maximum temperature that the 
fish fresh from the weirs will endure is about 75° F., the temperature 
of the water through which tlie cars are towed must be taken into 
(jonsideration, and the collection not be postponed until too late in the 
season. If the collection is prolonged, this difiiculty is obviated by 
using ice, as it has been found tliat by moderating the volume of water 
passing through the car and introducing it all through the ice compart- 
ment it is possible to keep a uniform temperature in the compartment 
in which the fish are held several degrees below that of the water iu 
the liver, thereby insuring the safe transfer of the salmon. 

1 he i)rinci])al sources of Dead Brook are two snuiU lakes, and on 
some of the tributaries there are considerable springs. While the 



MANUAL OF FISH-CULTURE. 33 

water is slightly purer than that of ordinary brooks, it is by no means 
so transparent as that of Craig Brook, and the bottom can hardly be 
be seen at the depth of 4 feet. This circumstance is regarded as favor- 
able. The in closure is located on the lower stretches of the brook, not 
more than half a mile from its mouth, with low banks on either hand 
and a very gentle current flowing over a bed that is for the most part 
gravelly but in i)art consists of a peaty mud that supi^orts a luxurious 
growth of aquatic vegetation. The general depth is less than 4 feet, 
but two of the pools are 8 feet deep and another is (> feet deep. Tlie 
width of the stream is from 20 to SO feet. The inclosure occupies the 
entire stream for a distance of 2,200 feet, embracing an area of about 
2i acres. At either end is a substantial barrier, consisting of wooden 
racks, which obstruct the current very slightly but confine the salmon 
securely. The lower barrier is provided with a gate, which swings open 
to admit boats, and at the upper barrier are the spawning-house and 
watchman's camp and a small storehouse. 

The temperature of the water during the summer months generally 
ranges between 60° and 70° F., but the surface temperature occasionally 
rises to 76°, 80°, and even 84°. During sultry weather the temperature 
at the bottom has been observed and in the deeper pools has been 
found to be notably lower than at the surface. Thus a temperature of 
75° at the surface has been found to be accompanied by G8° at the bot- 
tom ; 78° by 74° ; and 81° by 72°. It is probable that to the existence 
of these deeper pools the survival of the salmon through extremely hot 
weather may be ascribed. 

After their liberation in the inclosure the salmon are at first quite 
active, swimming about and often leaping into the air. This continues 
for several weeks, after which they become very quiet, lying in the 
deepest pools and rarely showing themselves until the approach of the 
spawning season. 

Most of the deaths occur during the first few weeks of their impris- 
onment, doubtless in consequence of injuries received in capture or 
during transfer, though high temperature in the inclosure itself about 
the time of the introduction of the salmon may be one of the causes of 
mortality. Fish that escape the dangers of June ai)pear to become 
acclimated and able to endure the high temperatures of Jidy and August 
without injury. 

Notwithstanding salmon enter the rivers in spring or early summer, 
ascending at once to their upper waters and there, in fresh water, 
awaiting the spawning season, fresh water is not essential to the activ- 
ity of their reproductive functions. At the Canadian fish-breeding 
station of Tadoussac, where salmon are almost the only fish cultivated, 
it has for many years beeti the practice to hold their brood fish in an 
inclosure supplied with salt water, which flows and ebbs through the 
barrier confining the salmon, and the develoi^ment of eggs and milt is 
in no wise unfavorably affected. 

F. M. 3 



34 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

THE EGG HARVEST. 

The uatural deposit of spawn by the Atlantic salmon in the rivers of 
the United States occurs during the months of October and November. 
In artificial operations at Dead Brook it has rarely been necessary to 
bej>in spawning before October 22, or to close later than November 15.* 

Dead Brook is commonly at a very low stage in August and Septem- 
ber, but it rarely fails that before October 20 there is a very material 
increase in volume. Whenever a sudden rise occurs, even in August 
or September, imprisoned salmon are at once excited to activity, and 
any aperture in the upper barrier sufficient to admit the body of a 
salmon is sure to lead to loss. As the breeding season approaches the 
sensitiveness of the fish to such influences increases, and a rise about 
October 20 is followed by a general movement of the salmon upstream 
in search of spawning-grounds. Advantage is taken of this circum- 
stance to entrap them at the upper barrier, where a small pound with 
a board floor and a barbed entrance, like that of a weir^ls constructed a 
few days in advance. The success of this trap depends on the stage of 
the water, and it is always the case that a portion of the fish fail to 
enter it, so that the final resort is to a seine, with which the recalcitrant 
salmon are swept out of pools where they are wont to lie. ' 

The fish are dipped from the trap or from the seine with soft bag-nets, 
such as are used in collecting them at the beginning of the season, 
assorted according to sex and condition, to facilitate manipulation, and 
placed in floating wooden pens, which are moored to the bank in front 
of the spawn-house. These pens are about 12 feet long and 4 feet wide, 
with grated sides and! floors, affording sufficient circulation of water, 
and, although indispensable for the convenient manipulation of the fish, 
the confinement in such narrow quarters leads to considerable chafing 
of noses and tails, and if long continued aflects the develojiment of the 
sexual functions of the female unfavorably, retarding the maturity of 
the eggs and even afiecting their quality. The capture -of the fish 
from the brook is therefore delayed to the point of risking the deposit 
of some of the earliest eggs in the brook rather than the possible 
injuries in the pens. 

The spawn-taking operations begin as soon as any females are ready 
to yield their eggs. A scarcity of males in breeding condition has never 
yet occurred at this station at the beginning of the season, and hardly 
ever at its close. Among the earliest captures there are always a few 
unripe fish, but invariably by the last day of October all are ripe. 

The spawning-house consists of a single, plain room, with two doors. 
From one of the beams hangs a steelyard ahd a bag, in which salmon 
are weighed. At one end is a stove, in which a fire is built in very 
cold weather. At the other end is a graduated board, upon which the 

* In Canadian rivers the dates are but a little earlier. Thus at the Gaspd hatchery, 
in the Province of Quebec, in 1894, the work of spawning began October 10 and closed 
November 2. 



Fish Manual. (To face page 34 




Plate 15. 



• ^ 


/ 




'A^ 


^J.£ 






fi 


1 




1 


II 


-fi^ jSHWb 




■P& J 


' '^^n^^^^^H 


hH&i! 


4 





Ripe female salmon. Male salmon 

EXAMINING FISH FOR STRIPPING. 




STRIPPING FEMALE SALMON. 



MANUAL OF FISH-CULTURE. 35 

fish are laid for measurement. At the front is a narrow table, on which 
the eggs are washed; and at the rear the entire side of the room is 
occupied by a series of shelves, on which the eggs are placed after 
fecundation and washing. 

The spawn taker, clad in waterproof clothing and wearing woolen 
mittens, sits on a stool or box, and on a box in front of him is a clean 
tin pan holding about 10 quarts, which has 'been rinsed and emptied 
but not wiped out. A female salmon is dipped up from one of the 
floating pens and brought to the operator, who seizes her by the tail 
with the riglit hand and holds her up, head downward. If unripe, the 
lish is retnrned to the pens; if ripe, the spawn will be loose and soft 
and will run down toward the head, leaving the region of the vent 
loose and flabby, and the operator, retaining his hold of the tail with 
his right hand, places tbe head of the fish under his left arm with the 
back uppermost, the head highest, and the vent immediately over the 
pan. At first the fish generally struggles violently and no spawn 
will flow; but as soon as she yields the eggs flow in a continuous 
stream, rattling sometimes with great force against the bottom of the 
pan. Shortly tbe flow slackens and must be encouraged and forced by 
pressing and stroking the abdomen with the left hand. It is better to 
use the face of the palm or the edge of the hand rather than pinch 
between the thumb and finger; the latter action, especially when work- 
ing down near the vent, is apt to rupture some of the minor blood 
vessels, with the result of internal bleeding, and it is better to leave 
some of the eggs behind to be taken another day than to rim the risk 
of such ruptures. 

If the fish in hand is fully ripe, nine-tenths of the eggs are obtained 
at the first trial. When the ojjeration has apparently gone far enough 
for the first day, the fish is laid in the weighing bag, and as soon as the 
weight is recorded is stretched upon the measuring board, whence she 
is returned to the water, after a stay of 10 or 15 minutes in the air, 
which results in no permanent injury. Both the weight and length of 
the fish and the weight of the eggs are recorded, together with any^thing 
remarkable connected with fish or eggs. 

Large salmon endure transportation and confinement less success- 
fully than smaller ones, and the record therefore shows large numbers 
of salmon from 29 to 31 inches in length, weighing, including eggs, from 
9 to 12 pounds, and yielding 2i to 3 pounds of spawn (0,000 to 8,700 
eggs), with now and then a fish 35 or 40 inches in length, yielding, in 
some cases, as many as 16,000 to 20,000 eggs. 

As soon as the spawn of a single female is taken, a male is brought 
to the spawn-taker and the milt expressed npon the eggs. The pan is 
then swayed and shakeu violently until the milt becomes well dis- 
tributed and in contact with every egg. If the (luantity of spawn 
exceeds 3 pounds it is divided and fecundated in two pans instead of 
one, as it is difficult to secure a good result if the «ggs lie in too great 



36 REPORT OP COMMISSIOiS'ER OF FISH AND FISHERIES. 

masses. The eggs are passed over to the washer, who repeats the 
swaying and the shaking, and, having weighed them, pours in a small 
quantity of water and goes through the mixing process for a third 
time. After this the eggs are immediately washed by pouring in an 
abundance of water and turning it ofl', and repeating the operation 
until the water appears quite clear, when the eggs are placed on the 
shelves in the rear of the apartment, to await the process of swelling. 
When the egg first comes from the fish it has a soft and velvety feeling 
to the hand, and the outer shell lies loose and slack against the yolk. 
The presence of water excites the shell to action ; its pores absorb water 
with such force that any foreign object coming in contact is sncked 
against it, and in consequence of this suction the eggs stick to the pan 
and to each other. In the course of 20 or 30 minutes this process is 
completed, the shell is swollen to its utmost extent and is firm to the 
touch, the space between the shell and the yolk is now filled with water, 
and adhesion to outer objects ceases. 

The eggs can now be laid upon trays and carried to the hatchery. 
No serious harm would ensue if the eggs should be disturbed during 
the process of swelling, but it is better not to spread them ui)on trays 
until they have attained full size and ceased to adhere to each other, 
and they are left on the shelves until the spawning for the day is over, 
when all are carried to the hatchery together. After the absorption of 
water the eggs must be handled very gently, as they are now suscep- 
tible to injury from sudden shocks, such as might ensue from pouring 
them from pan to pan, or setting the pan containing them down roughly 
upon a wooden table, and to guard against such injuries the tables and 
shelves are covered with old nets or other soft material. 

CONDITIONS AFFECTING FECUNDATION OF EGGS. 

While the spawn of a salmon is, with very rare excej^tions, in normal 
and healthy condition and capable of fecundation within the limits of 
the spawning season, occasionally a fish is found whose eggs are in 
some way defective. Sometimes they are developed unevenly, the 
ovaries containing eggs in various stages of growth, some matuie and 
some rudimentary; sometimes all the eggs of a fish are abnornrally 
small, and sometimes all have defects which render them incapable of 
fecundation. But among the thousands that have been manipulated 
at the station not 1 in 300 has had defects involving as many as 20 
per cent of her eggs, and in the spawn deemed of normal quality there 
can hardly be more than 1 defective egg in 400. Among the males no 
instance has occurred where there was reason to suspect the milt of 
being of defective quality if secured from a living fish. 

In 1872 experiments were made bearing on the duration of the 
capacity for fecundation of the eggs with interesting results. From 
eight lots of eggs taken from dead fish, the rates of imi)regnatiou ranged 
from 92^ per cent down to zero. From a fish that had been dead 2 



MANUAL OF FISH-CULTURE. 37 

hours 4,400 eggs were obtaiued, of wliicli only 58J per cent were capable 
of fecundation. In one instance eggs taken from a dead fish and kept 
until the morrow before milting remained so far in normal condition 
that 12i per cent were fecundated. In another case 400 eggs from a 
fish that had been dead 15 hours failed totally; and the same result 
was obtained with 2,200 eggs taken from four specimens killed two days 
before. 

The same experiments afford evidence as to the result of keeping eggs 
for various periods of time after they are taken from the fish, and 
eggs exposed to the air and guarded against contact with water appear 
to keej) better than in the organs of a dead fish. Thus, 200 eggs were 
kept in a pan without water for 12 hours after they were taken from 
the fish, and the application of milt then resulted in the impregnation 
of 00 per cent; of 200 eggs kept in the same way for 30 hours and then 
treated with fresh milt, 87i per cent were impregnated ; and of 100 eggs 
kept 4 days and then treated with fresh milt, 12 were impregnated. 

Milt taken from a living male and kept in an open dish for several 
hours retains its powers fully, bnt experiments with milt from dead fish 
have given almost wholly negative results. Kumerous experiments 
show that if eggs are merely covered by water, without eftbrt to secure 
intermixture or the washing off of the mucus that envelops them when 
pressed from the organs of the mother fish, tlieir susceptibility to fecun- 
dation may not be seriously affected by immersion 5 or C minutes; but 
if the eggs are stirred, so as to facilitate the washing off of the mucus 
and the access of pure water, immersion for 1 or 2 minutes may pre- 
vent impregnation. 

When thoroughly diluted with water the milt speedily loses its 
power, the effect being very marked at the end of 30 seconds; diluted 
with the mucus that accompanies the egg, it will remain effective for a 
long period. Where water has been carefully excluded, milt has been 
used successfully after the lapse of 12 hours with landlocked salmon, 
and this would probably hold with eggs of all kinds of salmon and 
trout. This propertj^ of the mixed mucus and milt has been utilized 
in impregnating masses of eggs when there is a scarcity of males, as 
sometimes occurs toward the close of the spawning season. In strain- 
ing the mixed mucus and milt from the pan of eggs, the lower strata, 
which are richer in milt than the upper, should be especially secured 
and the mixture kept in a convenient receptacle. The upper strata of 
the mixture should not be used, as the milt settles to the bottom. 
Fresh milt should always be preferred when obtainable. 

The eggs are washed as soon as the milt is thoroughly diffused among 
them, and this can hardly be done too speedily for the milt to act. A 
careful record of certain lots of eggs that were washed in special haste 
for experimental pnrposes shows that they were as well impregnated 
as those exposed to the action of the milt for a considerable period. 
Prolonged exposure to the milt has been found to affect the health and 
development of the embryo unfavorably. 



38 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

TRANSFER OF EGGS TO THE HATCHERY AND THEIR CARE. 

From Dead lirook the eggs are trail sfeired to the hatchery at Craig 
Brook station, about 2 miles, and spread on trays in the spawning- 
house. The trays are placed in frames, inclosed in boxes which are 
padded within to guard against concussion. In spite of all precautions 
some of the eggs are occasionally killed, though the trays are placed in 
pans of water and the eggs poured from the spawning-pans with the 
greatest care. The frames or " stacks " containing the eggs are placed 
at once in tbe troughs where they are to be developed. 

The trays are 12^ inches square, and constructed by attaching iron 
wire-cloth to light wooden rims with blocks at the corners, so that when 
piled up, one above another, there are narrow interstices on all four 
sides, through which water circulates freely. The rims of the trays 
are very slender, in order that they may never have buoyancy enough 
to float, which would necessitate some means of holding them down and 
increase the trouble attending their manipulation. Southern poplar 
(whitewood) is commonly used, and a rim ^ inch wide and | inch deep 
answers the purpose well, provided the wire be not very light. The 
corner pieces are ^ inch thick, and give the interstices just enough 
width to i)rovide an ample circulation of water, but not enough to 
allow the escape of salmon eggs, which are nearly 4 inch in diameter. 
Rusting is prevented by varnishing the wire-cloth with several coats of 
asphaltnm varnish, which works better if made very thin by the use of 
a large proportion of spirits of turpentine. The same varnish gives a 
clean and glossy surface to submerged woodwork, and the varnishing 
is extended to the rims of the trays, the "stack-frames," and interior 
surfaces of the troughs themselves. Material subject to rust should be 
used only with great caution. Wire or other metallic forms galvanized 
with zinc vary in quality. Total loss of eggs has been known to result 
from the use of galvanized wire-cloth when unvarnished. Careful 
experiment should precede the use of any particular brand. Tinned 
wire cloth is better, but whether siifhciently to, warrant the extra 
expense is the question. 

Ln developing eggs, in order to economize room, the trays are piled 
up 10 or 20 deep in frames that contine them only at the corners and do 
not hinder the free passage of water horizontally through the ''stack." 
About 2,000 Atlantic salmon eggs are placed on a single tray, and a 
trough of the ordinary length, lOi feet, therefore carries 140,000 to 
280,000 eggs, with suitable free space at either end. It is therefore an 
exceedingly compact apparatus and has the further advantage that it 
can be used in a very plain trough which can, with a few minutes' work, 
be transformed into a rearing-trough for young fish. For 10-tray stacks 
the trough is made of ])ine boards. 12f inches wide and inches deep 
inside, and is set up level, with the top about 30 inches Irom the floor of 
the room. 



manuai. of fish-culture. 



39 



The water is fed into one end through a wooden or rubber tube 
guarded by a wire screen, and is regulated by a simple swinging 
gate. The outlet is either over a wooden dam or through a hollow 
plug, either of which determines the heiglit of the water in the trough, 
which is always maintained just at the top of the covering tray or an 
eighth of an inch above it. 






Trough Arranged for EggB. 
Fig. 1, plan. Fig. 2, longitudiual section. 



o, supply-trough 
b, screen. 
d, 8 apply -pipe. 
/, egg-trough. 



j, down spout. 

r, cleats. 

s, slacks of egg-trays. 

t, waste-pipe. 



M, screen. 

V, outlet. 

w, wooden dam. 

X, water surface. 



For the regular picking and cleaning, and for other examinations, the 
stacks are removed from the trough to a table, where the trays can l)e 
taken out one by one, set over into an empty frame, and returned to 
the trough. This can be performed with ordinary caution at any stage 
of the development of the embryo, without doing the slightest injury, 
and after the delicate stage is passed the trays and their burden of 
eggs can be washed at the same time in a pan of water. 

WINTER CARE OF EGGS. 

The eggs pass the winter in the stacks. They are regularly picked 
over and the dead ones removed once or twice a week — twice during the 
first few weeks, on account of the comparatively high temperature then 
prevailing and the consequent rapid development of decay and growth 
of fungus. It depends, to a considerable extent, on the water tempera 
ture; the water at the beginning of the spawning season varies from 
50O to 55° F., and maintains a mean of 43° to 45*^ F. during the mouth 
of November. 

The color of a good egg, or of an unimpregnated egg that still retains 
its vitality, is a translucent salmon pink, with some variations in shade. 



40 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

It is possible, by placing it iu a favorable light, to get a fairly good 
interior view, including the detailed anatomy of the embryo. When 
the egg dies it turns chalky white, becomes wholly opaque, and in a few 
days, depending on the temperature, decay sets in, and sometimes a 
white water- mold or fungus begins to grow upon it. The mere decay 
of the egg would foul the water, thereby injuring the neighboring eggs, 
and the fungus established on the dead eggs may spread to the living 
ones. It is therefore essential that the white eggs be removed before 
they have time to do any injury. 

For egg-picking a homemade pair of tweezers, about 6 inches long, is 
used, made of any convenient wood and tipped with a pair of wire 
loops of a size to conveniently grasp the egg. The operator lifts the 
stack of trays carefully from the trough and, to save dripping, carries 
it on a wooden waiter to a well-lighted table of convenient height, on 
which stands an oblong pan, 14 by 18 inches, holding about an inch of 
water. 

The stack of eggs to be picked is placed at one end of the pan and 
at the other end is an empty stack-frame. The trays are examined one 
by one, dipped in the pan of water, picked (or cleaned by agitation 
when the eggs are in condition to endure the disturbance), and placed 
in the empty frame. The air of the room is kept at a low temperature 
during this process, and the water m the pan is often changed. 

The eggs when first impregnated are very sensitive to rude shocks and 
are handled with great care. Within a few hours the germ begins to 
develop; iu 10 days, at a temperature of about 40° F., the germ disk 
appears as a ring of color on the upper side of the yolk. At this date 
the uuimpregnated egg presents the same appearance and does not 
change much until its death, however long that may be deferred. In 
the impregnated egg, however, the germ-disk continually enlarges upon 
the surface of the yolk; the ring of color that marks its edge advances 
before it, passing quite round the yolk, and closing up on the posterior 
side. 

As early as the thirteenth day the diflerence between the impregnated 
ami uuimpregnated egg is quite plain to the unaided eye after a very 
little experience, and three or four days later the good egg is marked 
by a distinct line of color passing around the very middle of the yolk, 
a phenomenon never ai)pearing in an uuimpregnated egg. During 
this stage, while the embryonic disk is spreading around the yolk, 
tlie egg grows constantly more and more delicate, and liable to rupture 
of its tissues and consequent death on very slight disturbance; but 
later the tissues grow stronger, and when, about the thirty-flftii or 
fortietli day, the eyes of the embryo have assumed enough color to 
ap[)ear as two dark dots, the egg has attained hardiness enough to 
endure rougher handling. Thenceforward, until the near approach of 
the time for hatching, the work consists simi)ly in picking out the dead 
ones, occasionally rinsing out the sediment, and sometimes removing 
the uuimpregnated eggs. 



Fish Manual. ^To face page 40.) 



Plate 16. 




PICKING OUT DEAD EGGS 



PACKING SALMON EGGS. 




HANDLING EGG-TRAYS. 



MANUAL OF FISH-CULTURE. 41 

The latter procedure is attended to for the eiithx^ stock of eggs, but 
is of special importance in case of those that are to be transported. It 
may be performed any time after the good eggs become hardy — that is, 
after the eyes become black — but becomes easier late in the season. The 
unimpregnated eggs, which were at first fully equal in hardiness to the 
impregnated, lose in that respect as time passes, and finally are readily 
killed and turned white by a shock which does no injury to the impreg- 
nated eggs. When this time has arrived, the eggs are turned from the 
trays into spawning-pans with a moderate quantity of water, and 
poured from pan to pan back and forth a dozen times, each time falling 
a foot or more, and striking the bottom of the pan with considerable 
force, giving each egir, a severe shock. They are then returned to the 
trays and troughs and as soon as convenient are x)icked, and if the 
operation has been thorough almost every unimpregnated egg has 
turned white and is picked out, while the eggs in which the embryos 
are developing have not suffered at all. 

PACKING AND TRANSPORTING. 

Eggs may be safely transported as soon as the eyes have become 
thoroughly cohered, and until within a few weeks (five or six in cold 
weather) of the date for hatching. In shipments made too late the shells 
burst on the way and the embryos i)erish. The method of packing eggs 
at Craig Brook is to put them in layers alternating with wet sphagnum 
moss in shallow wooden boxes, placed in cases of a size to afford on 
all sides of the inner package a space of 2.^ or 3 inches, which ivS filled 
with some light, porous material that will form a good nonconductor 
of heat. 

The eggs are thrown from hatching-trays into a large rectangular 
pan, from which they are poured with water into tin measures which 
hold 2,500 each. A thin layer of moss is pUiced in the bottom of a 
I)acking-box. A little fine snow is sifted upon the moss, and on this is 
spread a piece of mosquito netting that has been soaked and rinsed in 
clean water. A measure of eggs is now poured on and spread out and 
covered by folding ovei' the edges of the netting, which now completely 
envelojis them. Next a layer of moss is spread, followed by snow, 
netting, and eggs, as before, and the series is repeated until the box is 
full. The moss must be sufficiently wet, so that with the melting' of the 
snow it shall have all the moisture it will hold, and no more, as it is 
very desirable to avoid the wetting of the outer packing. If the 
moss is too dry, the eggs may dry to the extent of l)ecoming indented, 
and the same result may come from crowding the moss in too hard on 
the eggs, though it should be pressed in so tightly that the eggs will 
not slide out of place if the case is turned for a moment on its side. 

The temperature of the packing-room is below 50° F., and packing 
materials are kept in a i)lace which is cool, yet not much below the 
freezing-point. Salmon eggs packed as above commonly go a three 
days' journey without completely melting the snow that was sprinkled 



42 



REPORT OF COMMISSIONER OP PISH AND PISHERIES. 



under the eggs, and on several occasions eggs of landlocked salmon 
have been carried acioss tlie Atlantic in prime condition, without 
repacking or special attention. 

The packiug-boxes are made of thin pine or fir, 12 inches wide and 15 
inches long — | inch thick boards being used for tlie end pieces and 
J-inch for the other parts — and hold in a single laj^er, without crowding, 
2,500 eggfi. The deepest are 3.^ inches deep and take four layers, or 
10,000 eggs, in a box. To make uj) a shipment of 40,000 eggs, four boxes 
are piled u}) and secured together by tacking strips of wood against 
the ends, with a cover on tlie upper box, and this package placed in 
the case. For a shipment of 80,000, two of the 40,000 packages are put 
side by side in a larger case, and the ])roporti()ns selected for the inner 
boxes are such that the case required is of convenient form. 




^^^^^W?F^h^. 









Z:^ 







^^! ^^<ia^^s^_^^9o^of^^^^^?s^^^^sgei3(i<i^^\ 



ooa%i^oa9<s9^3<)osai 







\^^^^^^^^^^^^^^^^S%^ 



'77 ^;///////?///7/7a7//77// ////////'/ //• //// //>////////////// 

Longitndiual section of a case of Atlantic .Salmon egi;s. 

Different mosses can be used for packing, but none are so good as 
the sphagnous moss that can be found in swamps and bogs in mosi 
regions of high latitude or considerable elevation. Fresh moss is 
preferable for a bed foi' the eggs, though dead, dry moss may be moist- 
ened and used with good results. 

The moss is gathered in August or September, dried on the ground, 
and stored in sacks or in bulk until wanted. It retains its freshness 
through the following winter, not heating like most organic materials. 
It is exceedingly liglit, and the best nonconductor known, with the 
possible exception of asbestos. It is used dry in the outer i)acking 
mainly to save weight, but when protection against freezing is all that 
is sought, wet moss is better, as frost penetrates wet moss more slowly 
than dry. When moss can not be had, there are many substitutes 
which may be used for the jirotective envelope, such as dry forest 
leaves, chaff from a hjiymow, chopped hay, or even crumpled paper,* 
but the latter should not be allowed to become wet. 



MANUAL OF FISH-CULTURE. 43 

HATCHING. 

As the time for hatching draws near, the eggs are placed on trays 
provided with legs or some other support to keep them up from the 
bottom of the trough. Brass nails driven into the under sides of the 
tray rims are good temporary legs, and after the hatching is over they 
are readily removed and the necessity of a special set of trays for 
hatching is avoided. When there are plenty of troughs, these trays 
stand singly on the bottom of the trougli, but when it is necessary to 
economize room two or even Three aie disposed one above another. 
When no necessity exists for e(U)nomy of space, 4,000 eggs are allowed 
a whole trough, which is at the rate of 400 to the square foot; 2,000 
or even 5,000 to the square foot may be carried through hatching and 
the entire sac stage, but the latter number involves risky crowding. 

The hatching is sometimes expedited by giving eggs that are just at 
the hatching point a decided shock, similar to that given at an earlier 
date to kill the unimpregnated ones; also by the temporary stoppage 
of the water supply. But at Craig Brook it is the custom to lay the eggs 
out in good season and allow them unlimited time in which to hatch, 
sometimes a week, sometimes two weeks. The earliest lots comiaonly 
hatch the latter part of March, and it is not often that any remain 
unhatched after April 20. The mean duration of the egg stage is 
therefore about 157 days, during which the mean temperature of the 
water has been about 37° F. While hatching is progressing, the outlet 
screens are closely watched to keep the empty shells from clogging 
them ui); for when a considerable part of the screen is clogged the 
force of the current through the open spaces is greatly increased, and 
the soft and yielding sacs of the fish are liable to be drawn through 
the meshes. 

THE SAC STAGE. 

When the shell breaks, though it has been coiled up in a space less 
than ^ Inch in diameter, the trunk of the newly hatched salmon at once 
sti'aightens out to a length of about f inch. The yolk, scarcely dimin- 
ished from its original size, hangs beneath and constitutes the greater 
part of the bulk of the fish. The young salmon is for a while more 
unwieldly than a tadpole. When frightened he sculls about with great 
energy, but makes slow progress and is fain to lie on his side on the 
bottom of the trough or crowd with his companions into a corner. Tbe 
sac is a store of nutriment, which is gradually absorbed into the other 
parts of the fish; and so long as it lasts the young salmon will not eat. 
The interval between hatching and total absorption of the sac varies 
with the temperature, the mean at Craig Brook in April and May being 
about six weeks. 

As time passes the embryo fish grows more and more to resemble the 
adult, his body acquires strength, and his fins assume form and become 
more effective as organs of propulsion. At last his digestive system 



44 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



assumes its functions and rouses the desire for food. Until tliis time, 
intent only on hiding, the fry have clung obstinately to the bottom and 
to the dark corners, but now they scatter about through the water, 
with lieads upstream, watching for prey. This indicates that they 
must be fed. During this period of his growth it is simply necessary 
to see that the young ftsh has plenty of water, that there is no hole or 
crevice into which he can be drawn by the current, and that he is pro- 
tected from enemies, such as large fishes, minks, rats, kingfishers, and 
lierous. If not in a house, well- fitting covers must be provided to the 
troughs and impassable screens command both ends. The screens are 
of fine wire- cloth, 12 or 14 meshes to th6 linear inch, and present a sur- 
face of 14 square inches to each gallon oi" water passing through them 
each minute. Thus, if there are 4 gallons of water passing through the 
trough each minute the portion of the screen beneath the surface of the 
water must measure as much as 56 square inches, and if the screen is 
12 inches wide the water must be 4f inches deep on the screen. 




Atlantic Salmon, recently hatclied. - 
REARING. 

The leading feature of the work of the station is the rearing of fry to 
the age of six or eight months. The fishes reared are mainly Atlantic 
salmon, but landlocked salmon, American brook trout, European brook 
trout, rainbow trout, steelhead trout, American lake trout, Swiss lake 
trout, Scotch sea trout, and saibling have also been handled. The fish 
are fed wholly on artificial food from about June 1 till October or 
November, when they are mostly liberated. To a limited extent they 
are kept in artificial ponds, but troughs of the same form and dimen- 
sions as those already described for use in developing the eggs and in 
hatching have given satisfactory results and have been adopted for the 
most part. Each trough is provided with a changeable outlet screen 
and below the screen discharges the water through a hole in the bottom, 
into which is fitted a hollow plug, the height of which determines the 
depth of water in the trough. The hollow plug plays an important part 
in the daily cleaning of the trough, which will be referred to further on. 

The use of the troughs in the open air, whic;h, in the absence of com 
modious buildings, is a necessity, compels the constant use of covers to 
keep out vermin 5 and wooden covers in pairs, running the whole length 



MANUAL OF FISH-CULTURE. 



45 



of the trough, hinged to its sides, and, when closed, assuming the form 
of a roof at an angle of 45°, were Anally adopted. These covers are 
made of thin boards, g inch thick, sawed in narrow pieces, which are 
put together so as to leave in each corner two cracks open ^ inch wide 
for the admission of light when the covers are closed. When open they 
may be fixed in an upright position, thus increasing the height of the 
sides and guarding against the loss of lish by jumping out. 



rr""^ — ' 


Tl 


Tig.l 


!-.| 




1 n 


h 
a 


If 


f 9 

e 




i 

i 

o 


Cd 









rig. 2. 




? 



Tiouo'lis arranged for Rearin< 



Fig 
with r 

6, 

<", 
/, 

h. 



1, plan. Fig. 2, longitudinal section. Fig. 3, cross-section near foot of trough. Fig. 4, inlet, 
ocking gate. Fig. .'), elevation of lower end. 



supply trough. 

screen. 

rocking gate. 

supply-pipe. 

water-lioard (to spread the water and throw it down). 

fish -trough. 

gripe, to prevent spreading of sides. 

outlet screen. 



i, hollow'outlet plug. 

j, down-spout. 

k, supports. 

I, cover. 
■)n, cover open (hanging). 
71, cover open (upright). 
p, cover closed. 
(J, end hoards (closing aperture). 



Water is furnished through rubber or wooden pipes f inch in diame- 
ter, and the bore of the hollow plug at the outlet is IJ inch or larger. 
The inflow is regulated by an oscillating or rocking gate, which is set 
to admit the desired volume of water. The trough is set with the 
upper end an inch or two higher than the other, to facilitate cleaning 
out, and the water is kept during the summer about 4 inches deep at 
the lower end. 



46 



KEPUKT OF COMMISSIONER OF FISH AND FISHERIES. 



The troughs are supported by a suitable framework at a convenient 
height from the ground and arranged in pairs with their heads against 
a long feed-trough, constructed of pine boards and perforated on the 
side by the feed-i)ipes, over each of which is a capacious screen to pre- 
vent clogging by leaves or other floating debris. A frame G by 12 
inches, covered on its outer side by wire-cloth of J inch square mesh, 
answers the purpose of a screen so well that water from an ordinary 
brook can be admitted to the feed-trough without previous filtering or 
screening and with little or no danger of a stoppage of water in any 
of the fish troughs. Such screens over the feed-pipes might be made 
the sole dependence, were it not that the labor attending their cleaning 
would be greater than that required by a separate filter or screen. 



CondLtit to lower Zevet. 



n 



/VjA. trxniaK 



n 



^^ 



Scale of feet. 



% 



D 

Stand of Troughs for Rearing Atlantic Salmon. 

The system represented here by 12 troughs in two series may be 
extended to many hundreds of troughs in four (or more) series, each 
series On a different level and receiving- water from the series next 
above, the fall from one to another being about 4 feet. In the drawing 
the series of 6 troughs on the left is supplied with water directly from 
tlie upper "feed-trough" (i. e., supply-trough), and they discharge into 
a catch-trough, from which the water is carried to the supply-trough 
("feed-trough") of the lower level. If the aqueduct supplies more 
water than the upper series of troughs can use, the surplus passes by 
way of thp " overflow" directly to the catch-trough and thence to the 
supply-trough of the second series. With a fall of 4 feet, the catch- 
trough and the conduits that lead from it are below the walks which 
give access to the troughs on both sides and at the lower end. 

The number of fish assigned to a single trough is ordinarily 2,000, 
and the volume of water given them is commonly T) gnllons per minute. 
Generally the water is used but once in troughs and is discharged 



MANUAL OF FISH- CULTURE. 47 

iuto conduits leading to ponds where larger fisli are kept ; but a stand of 
100 troughs has lately been set up with the design of using all the 
water twice; and for many years there has been one system of 52 
troughs, arranged in four series, which use in succession the same 
water, the young salmon thriving quite as well in the fourth series as 
in the first. 

On one occasion a few of them were maintained for several weeks in 
the warmer water of a neighboring brook, where a trough was set up 
and stocked with 100 young salmon taken from one of the troughs at 
the station Julj^SO. The temperatures observed between 1 and 4 p. m. 
in the fish-trough on successive days from July oO to August 14, not 
including August 1 or 10, were as follows: 79°, 75°, 77°, 79°, 82°, 8Uo, 
78°, 76°, 70°, 70°, 74°, 74°, 74o, 74°, F. 

The fish were fed the same as the lot out of which they were taken, 
except that thej^ received food only once a day instead of twice, and 
were returned to the station October 7 without a single loss during the 
experiment. Moreover, they were all weighed October 10 and found 
to average lOO.G grains, whde those of the original lot that had remained 
at the station, with a temperature between 50° and 71° F., averaged 
only 50.1 grains. While the greatly increased weight of the fish kept 
in the stream was owing in part to more space, as the 100 had as large 
a trough as 1,505 at the station, the higher temperature was undoubt- 
edly one of the factors that contributed to the gain in weight, and it is 
at least plainly shown that the warm water was not unhealthful. 

Though small ponds, excavated by the former proprietor, were in 
existence at the station and used to some extent for rearing young fish 
in their first summer as far back as 1888, and older fish have been kept 
in small ponds each season since that, it was not until 189G that enough 
pond work was donie to furnish data of importance. 

The ponds for rearing Atlantic salmon are among the series known 
as the "south ponds," occupying a smooth piece of ground sloping 
toward Alamoosook Lake at a grade of 1 in 8. Formerly it was mostly a 
swale, watered by a copious spring at its head. This series comprises 10 
ponds of rectangular form, about 50 to 90 feet long and 15 feet wide, with 
a depth of 2 or 3 feet. The water supply of those used for Atlantic sal- 
mon is derived from Oraig Brook by an aqueduct tapping it at a point 
where two parts of Craig Pond water are mingled with one part spring 
water, being substantially the same as the water supplying the most 
of the rearingtroughs. From 5,000 to 10,000 fish that have been fed in 
troughs during the early part of the feeding season are i)laced in each 
pond, and for the remainder of the season are fed the same food that is 
given to the fish left in the troughs; and the results indicate that the 
stock of fish might be safely increased. 

"While the greater part of the salmon reared at Craig Brook are 
liberated in October, when about seven months old, in 1891-92 about 
10,000 were carried through the winter, most of them in tanks sunk 
in the ground, and nearly as many have been wintered some other 



48 REPORT OF COMMISSIONER OF FISH AND FISHERIES, 

seasons. Fish may also be kept all winter in troughs in the open air 
by occasionally sj)readiug blankets over them in exceptionally cold 
weather, and keeping the conduits carefully covered. 

Tlie fish surviving the summer season are generally counted and 
weighed in October, in the following manner : A large number of them 
are dipped up from a trough in a small dip net made of cheese-cloth, 
and from this, while it is hanging in the water in such a manner that 
the fish can not escape, they are dipped out a few at a time, in a small 
dipper or cup, counted, and placed in another bag net until a sufficient 
number (generally 200) are counted, when they are lifted out of the 
water, held a moment in the air to drain, and all turned quickly into 
a pail of water which has previously been weighed. With care no 
appreciable amount of water goes with the fish, and the increase in the 
reading indicates their weight with a fair approach to accuracy, and 
with care and celerity of action it is quite safe for the fish. 

The size attained by the fish varies greatly, being aftected by the 
water, the space allowed, the feed, and i^erhaps by hereditary influences; 
but when seven mouths old a trough-reared salmon is generally from 
2^ to 3 inches long and weighs from 35 to 100 grains, the maximum being 
about 130 grains and the minimum as low as 7 grains, the general 
mean for 1890 being 45.8 grains. Salmon reared in ponds have been far 
more thrifty, their gentral average in 1896 being 101 grains.* The 
losses in ponds from July to October were rather heavy, being 11.7 per 
cent, owing to depredations of frogs, birds, and cannibal fish. The 
losses in the troughs during the entire season were 9.1 per cent, but 
most of these were in the early stages of fryhood. After July losses in 
troughs are always very light. 

MATERIALS FOR FISH FOOD. 

At Craig Brook station there have been used butchers' offal, flesh of 
horses and other domestic animals, fresli fish, and maggots. Experi- 
ments have also been made with i^ickled fish, blood, fresh- water 
mussels, mosquito larvae, miscellaneous aquatic animals of minute size, 

*A very interesting comparison between the results of rearing in troughs and 
ponds is afforded by the record of two lots of steelhcad trout during the season of 
1896. All the fry of this species that were devoted to rearing were fed in troughs 
until July 21', wlien some of them were transferred to a pund which has an area of 
about 1,100 8(|uare feet and another lot was kept in a trough. The two lots were fed 
exactly alike, about one-sixth of their nutriment being live maggots, and tive-sixths 
chop])ed meat, liver, and other butchers' offal. November 7, the lot in the trough 
was overhauled, and the 762 survivors found to weigh 10 pounds 4 ounces, or an 
average of 94 grains. Three days later the pond hsh were seined out and the 7,398 
survivors fouiul to weigh 23.5 pounds 10 ounces, an average of 223 grains. It is not 
beliexed that natural ibod occurring in the pond contributed much to this result, and 
it Avould ap))ear tliiit the controlling factor in the case VA'as the space afforded the 
fish. Leaving out of the account the diti'erenee in depth, in the pond there were less 
than 7 lish to each S(|uare foot of area, while in the trough, a\ hich luul an area of 
about 11 s(]uare feet, there were to each S(|uaro foot 69 fish. A similar illustration 
was furnished by 41 rainbow trout of the hatching of 1896 that got astray in one of 
the ponds and were taken out November 11, Aveighing 480 grains each. Those 
of the same age, reared in troughs, attained during the season only a weight of 136^^ 
grains each. 



MANUAL OF FISH-CULTURE. 49 

flour, and middlings. The butchers' offal comprises livers, hearts, and 
lights, which are collected from the slaughter-houses twice or thrice 
weekly, and preserved in refrigerators until used. 

The flesh of old and worn-out horses has been used each year since 
1892 in the same way as the butcher's offal, with very satisfactory 
results; the parts that could be chopped readily have been fed direct 
to the fish so far as needed, and other parts have been used in the 
rearing of maggots. 

Next to chopped meat maggots have constituted the most important 
article of food, and their systematic production has received much 
attention. A rough wooden building has been erected for this branch 
of the work, and one man is constantly employed about it during the 
summer and early autumn months. The maggots thus far used are 
exclusively flesh-eaters, mainly those of two undetermined species of 
flies; the first and most important being a small, smooth, shining green 
or bluish-green fly, occurring in early summer and remaining in some- 
what diminished numbers until October; and the otlier a large, rough, 
steel-blue fly that comes later and in autumn becomes the predomi- 
nating species, having such hardiness as to continue the reproduction 
of its kind long after the occurrence of frosts sufficiently severe to 
freeze the ground. 

To obtain maggots meat is exposed in a sheltered location accessible 
to flies during the day. When well stocked with the spawn of the flies 
it is placed in boxes, which are set away in the " fly-house" to develop; 
when fully grown, the maggots are taken out and fed at once to the fish. 
Stale meat, parts of the butchers' oft'al and of the horse carcasses not 
adapted to chopping; fish, fresh, dried, or pickled; fish pomace from 
herring-oil works, and any animal refuse that comes to hand, are used 
to entice the flies and afford nourishment for the maggots. Fresh fish, 
when not too watery or oily, like alewives and hevring, is very attract- 
ive to the flies, and in proper condition may serve as well as fresh meat. 
Fish dried without salt or smoke and moistened before using is, when 
free from oil, a superior article. Its preparation presents some diffi- 
culties, but in winter it is easily effected by impaling whole fishes on 
sticks and hanging them up under a roof where they will be protected 
from rain without hindering the circulation of the air; in this way 
many flounders and other refuse fish from the smelt fisheries have been 
dried. 

It is usually necessary to expose meat but a single day to obtain suf- 
ficient fly spawn; thelarvpe are hatched and active the next day, except 
in cool weather, and they attain their full growth in two or three days. 
To separate them from the remnants of food the meat bearing the fly 
spawn is placed on a layer of loose hay or straw in a box which has a 
wire-cloth bottom, and which stands inside a slightly larger box with a 
tight wooden bottom. When full grown, the maggots work their way 
down through the hay into the lower box, where they are found nearly 
free from dirt. 

r. M. i 



50 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

When youni? salmon or trout first begin to feed tlieyare quite unable 
to swallow full-grown maggots, aud small ones are obtained for tliem by 
putting a large quantity of fly spawn with a small quantity of meat, 
the result being that the maggots soon begin to crowd each other aud 
the surplus is worked off into the lower box before attaining great size. 
No attempt is, however, made to induce the young fish to swallow even 
the smallest maggots until tliey have been fed a while on chopped 
liver. 

Maggots are produced and used in considerable nuuibers, sometimes 
as many as a bushel in a day. The fish eat them eagerly, and appear 
to thrive on them better than on dead meat. Having great tenacity of 
life, if not snapped uj) immediately by the fish they remain alive for a 
day or two, and, as they wriggle about on the bottom, are almost cer- 
tain to be finally eaten, which is a great gain in cleanliness and economy, 
as the particles of dead flesh falling to the bottom are largely neglected 
by the fish and begin to putrefy in a few hours and foul the troughs. 
As the growth of maggots can be controlled by reguUition of the tem- 
perature, they may be kept all winter in a pit or cellar and used as food 
for fish confined in dee[) tanks not easily cleaned. 

In the rearing of maggots the offensive odors of decaying flesh may 
be partly overcome by putting it away in boxes, after the visits of the 
flies, and covering it with pulverized earth. Only flesh-eating maggots 
have yet been tried, and the trouble may possibly be rectified by culti- 
vating the larvic of other species, such as the house-fly, the stable fly, 
etc., or a little white maggot known to grow in heaps of seaweed, if 
their rate of growth is found to be satisfactory. 

Occasional use has been made of fresh fish for direct feeding, but when 
thrown into the water after chopping it breaks up into fibers to such 
an extent that it is not satisfactory, unless in a coarsely chopped form, 
for the food of large fish. A few barrels of salted alewives have been 
used, and, if well soaked out and chopped, they are readily eaten by the 
larger fish and can be fed to fry, but are less satisfactory with the latter, 
and, like fresh fish, break up to such an extent that they are only to be 
regarded as one of the last resorts. 

Fresb -water mussels, belonging almost wholly to a species of Unio, 
have been occasionally gathered with nets or dredges in the lake close 
to the station and opened with knives and chopped. The meat is 
readily eaten by all fishes and appears to form an excellent diet. It is 
more buoyant than any other article tried, sinks more slowly in water, 
and gives the fish more time to seize it before it reaches the bottom; 
but the labor involved in dredging and shelling is a serious drawback. 

During the seasons of 1886 and 1888 some use was made of mosquito 
larvae, collected from pools of swamp water by means of a set of strain- 
ers specially devised for the purpose and from barrels filled with water 
disposed in convenient places near the rearing-troughs. The larvfe (or 
pupfe) were strained out and fed to the fish. No kind of food has been 



MANUAL OF FISH-CULTURE. 51 

more eagerly devoured, and apparently no other food has contributed 
more to the growth of the fish; but the time expended in collecting is 
out of all proportion to the quantity of food secured. Perhaps a series 
of breeding-tanks arranged in proximity to the fish-troughs, into which 
the water containing the larviie might be drawn when desirable by the 
simple opening of a faucet, would reduce the labor involved. 

Middlings and fiour have been tried in combination with blood from 
the shambles, but did not appear to satisfy the fish so well as the vari- 
ous forms of meat, and their use has, therefore, not been continued. 
They were fed in the form of a pudding composed of two parts blood 
and one part flour or middlings, cooked carefully to avoid burning, 
and the mixture was then passed througli a meat-chopper and ladled 
out with a spoon, like otiier chopped food. 

The growth of live food in the ponds themselves in which the fish are 
maintained has been the subject of study. Ponds several years old 
and well stocked with vegetation were at one time devoted to these 
experiments. They had been empty during the preceding winter, and 
in the spring were fertilized with various sorts of animal and vegetable 
refuse. They were stocked with different species of Crustacea native 
to the region, including shrimps {Gammarus) and entomostraca, of the 
genera DcqyJinia, Ceriodaphnia, Sida, Cyclops, Polyphemus, etc., which 
were systematically collected from open waters by nets and other appa- 
ratus and placed in the ponds. These forms all multiplied there, some 
of them enormously, but no means was fimnd of inducing continuous 
or frequent reproduction of them, and the young fish soon exhausted 
the supply. 

In serving the food the attendant carries it with the left hand — in a 
2-quart dipper if chopped meat, in a larger vessel if maggots — and, 
dipping it out with a large spoon, strews it the whole length of the 
trough, being careful to put the greater portion at the head, where the 
fish nearly always congregate. Finely chopped food, for very young 
fish, is slightly thinned with water before feeding. 

It is usual to feed the meat raw except the lights, which chop better 
if boiled first; but occasional lots of meat, on the point of becoming 
tainted, are boiled to save them. All meats fed directly to the fish are 
first passed through a chopping-machine. To fish just beginning to 
eat, food is given four times a day, or in some cases even six times, but 
as the season progresses the number of rations is gradually reduced 
to two daily. In winter such fish as are carried through are fed but 
once a day. 

CLEANING THE TROUaHS. 

The troughs are all cleaned daily. When the hollow plug is drawn 
the water rushes out rapidly and carries most of the debris against the 
screen. The fishes are excited, and, scurrying about, loosen nearly all 
the dirt from the bottom; what will not otherwise yield is started with 
a brush, but after the first few weeks the brush has rarely to be used 



52 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

except to rub the debris through the outlet screen. Owing to the incli- 
nation of the trough, the water recedes from the upper end until the 
lishes lying there are almost wholly out of water, but, although they are 
left in that position sometimes for 10 or 15 minutes, no harm has ever 
been known to result. 

TRANSPORTATION AND LIBERATION OF YOUNG SALMON. 

The salmon produced at the station have, with few exceptions, been 
liberated in the Penobscot River or its tributaries, and more than 90 
per cent of them in small tributaries within 10 miles of the station. 
They have been spread about in streams and lakes, at all accessible 
points. They are transferred in tin cans, holdiug about 8 gallons, with 
an extreme height, including neck, of 17 or 18 inches, and a body 15^ 
inches in diameter and 10 inches deep, making a very broad and low 
can, well adapted to the use to which it is put. Its great width favors 
aeration at the surface, and a good deal of dashing about of the water 
when on the road. The cans are filled to within about an inch from the 
shoulder, giving opportunity for the water to swash about and aerate 
itself. Into such a can are put from 200 to 400 Atlantic salmon seven 
months old, more or less, according to the size of the fish, the tempera- 
ture of the air, and the weather. The ordinary load is about 300 when 
the temperature of the water is 52° to 54° j?.^ making 37 fish per gallon. 
Such loads are entirely safe for the conditions attending the work. 
The motion of the wagon in which they are carried keeps up the aera- 
tion of the water, so that the fish can not exhaust the air. Should the 
cans stand still a very long time aeration is effected by a force-pump 
which draws the water from the can and returns it through a tube so 
that it strikes upon a deflector by which it is broken and scattered in 
spray. The suction hose is covered with a roomy wire strainer, so that 
the fish are not drawn in. 

DISEASES. 

Salmon in all their stages of growth are subject to a variety of dis 
eases. White spots sometimes occur on the eggs attached to the shell, 
but have no hold on the embryos, so that when the shell is torn off the 
white spot is seen as a cluster of globular white masses on its inner 
surface. These appear to be vegetable parasites, perhaps fungoid in 
their relations, and are never seriously abundant. Other white spots 
are connected with the yolk-sac itself. These are more serious, but 
while they result in the death of many embryos, they are .^y no means 
always fatal. In 1896 there were hatched at the station some rainbow 
trout that were badly spotted on the sac. A portion of the fry were 
divided into three lots for experiment: {a) Without spots; (b) moder- 
ately spotted; (c) badly spotted. They were kept separate through the 
season, and a fair percentage survived, as follows: Of lot a, 55 per 
cent ; of lot 6, 59 per cent ; of lot c, 43 per cent. In the fall they were 



MANUAL OF FISH-CULTURE. 53 

all weighed, and it was found that lot c liad made a slightly better 
growth than lot a. 

One of the most uncontrollable diseases attacks salmon fry midway 
in the sac stage, and finishes its work before the complete absorption 
of the sac. The most evident symptom is the appearance of scattered 
white spots in the sac; the tish cease to try to hide, but lie scattered 
about on the bottom of the trough ; the spots increase in size, coalesce, 
and finally occupy large areas, especially in the tip of the sac, which 
becomes quite white. Soon after this the fish dies. The attack on a 
lot makes rapid progress; for instance, a lot of 2,000 in which, up to 
April 22, the losses had been from 1 to 9 daily, showed 17 dead on the 
23d, and five days later 300 died in a single day. In 1890 this epi- 
demic attacked especially the fry of Atlantic salmon, destroying about 
a third of them; it also destroyed many landlocked salmon, and some 
other species suffered heavily about the same time. In 1891 there was 
not a trace of it. In 1892 it returned again, and out of 305,353 fry of 
Atlantic salmon it left but 3,874, and these were by no means healthy; 
but it attacked only Atlantic salmon. Salt and mud were tried as 
remedies, but though the progress of the disease appeared in some 
instances checked thereby, no permanent benefit resulted from their 
use. 

In 1890 this epidemic appeared to run iu families. There was evi- 
dence tending to show that all the eggs coming from a particular mother 
would have a common degree of liability to the disease — some families 
be."ng exterminated by it, some only decimated, and others able to resist 
it altogether. It did not appear to be infections, as several lots of fry, 
separated by screens, would occupy a single trough, and in some cases 
those at the head of the trough would be totally destroyed, or nearly so, 
and those below them escape from attack. 

The only other diseases of Atlantic salmon that demand notice here 
are connected with the so-called fungus, belonging to the groap of 
water molds called Saprolegniw, and probably to the genus Saprolegnia, 
one species of which, S.fcrax, is noted as the cause of very destructive 
epidemics among the adult salmon of Scotch and English rivers. The 
species that attacks tish eggs is well known to every flsh-culturist as 
a fine white growth of a cottony or woolly appearance that forms upon 
dead eggs, and when neglected spreads out so as to envelop in its 
threads a great many of the living eggs surrounding it. It is by no 
means certain that all such growths belong to one species or even to 
one genus, but they are nuich alike in structure and growth and live 
upon animal and vegetable matter, either as parasites attacking living 
matter or as saprophytes attacking only dead and decaying matter. 
There has never been serious trouble with this fungus at Craig Brook 
station, and great loss from it can only occur m consequence of neglect 
of the duty of picking out the dead eggs. An instance of its attacking 
a living e,gg except by reaching out from a dead one is unknown. Fish 



54 REPORT OF COMMISSIONER OP PISH AND FISHERIES. 

several months old are sometimes afflicted with a similar growth, which 
may possibly be not the original cause of the disease, but ouly an 
attendant symptom. Such an attack was experienced at Craig Brook 
in July, 1888. The fry of Atlantic salmon were the sufferers and the 
mortality was considerable, but it yielded promptly to a salt bath. 

The occurrence of fungus on wounds, even on such as result from 
the abrasion of the skin or the loss of a scale, is very common, but such 
cases are rarely fatal, though no remedy be applied. The only serious 
attack of fungus on adult salmon occurred during the experimental 
work at Craig Brook in 1871. The first inclosure made to receive the 
breeding fish was a small and shallow one, made by damming the brook 
itself at a point where its volume consisted of about 30 per cent of 
spring water. The fish had suffered considerably from the handling 
necessary in bringing them so far and from the rough character of the 
experimental cars in which they were transi)orted. The first of them 
were placed in the inclosure June 8. On the 12th 2 of them died, on 
the 13th 2 more, and by the 17th 14 were dead out of 41 received; by 
the 20th the mortality had increased to such a point that it became 
evident that not a single salmon would survive unless some change was 
made in the mode of confining them, and they were all removed and 
placed in other quarters. Nine of them, already so badly diseased as 
to be considered hopeless cases, were turned loose in Craig Pond, and 
part of these recovered and spawned in the autumn following on a 
gravelly shore, where some of them were taken and found to bear the 
well-healed scars of their ugly sores. 

The symptoms noted were sluggishness and heedlessness; an inclina- 
tion to swim near the surface of the water; a white, filmy appearance 
of the eyes, which seemed to be accompanied or followed in many cases 
by blindness; a white fungoid growth on the abraded tips of the fins 
and wherever the scales had been rubbed off; white blotches breaking 
out on all parts of the body, even where there had been no mark of 
injury, particularly on the head, proving on examination to be patches 
of white fungus, which, on the parts of the body covered by scales, 
grew underneath the latter and pushed them from their places. 

Experiments in confining salmon in other waters the same season 
turned out successfully, and it seems that the most important condi- 
tions in the case were these : The area of the fatal inclosure was about 
a quarter of an acre; the water was partly from springs and was so 
exceedingly transparent that a pin dropped into it could be readily 
seen at a depth of G feet, so that there was practically no protection 
from the rays of the June sun ; the fish had been transported in a com- 
mon dory with holes bored in the bottom to admit water, a very inferior 
sort of car compared with those now in use; they had been transported 
a long distance and passed three separate locks and had tiually been 
hauled in a tub on a cart over rough ground from Alamoosook Lake to 
the inclosure. 



Fish Manual. (To face page 54.) 



Plate 17. 




FUNGUS ON SALMON EGG 
( Enlarged 9 limes.) 



FUNGUS ON SALMON EGG, BEARING REPRODUCTIVE ORGANS. 
(Enlarged 9 iimes.) 




REPRODUCTIVE ORGANS OF EGG FUNGUS. 
(Enlarged 1 50 times ) 



MANUAL OF FISH-CULTURE. 55 

The conditions at Craig Pond, where some of the worst cases recov- 
ered, were these: An area of 231 acres; a maximum depth of 09 feet; 
exceedingly pure and transparent water, like that of the inclosure. 

At two of the other iuclosures tried that summer, where there was 
no attack of fungus, the water was brown and dark, like that of ordi- 
nary brooks and ponds, and in the remaining one it was intermediate 
in character. 

These facts point strongly to the character of the water as the cause 
of the fatality of the disease, and especially to its pellucid character, 
which exposed the salmon to an extraordinary glare of light, whereby 
the growth of the pest was greatly encouraged. The recovery in the 
transparent water of Craig Pond was rendered possible by the great 
depth of the water, through which but a small fraction of the light of 
day could j)enetrate. No doubt the salmon liberated there at once took 
refuge in the deeper parts. The suggestion naturally arises that arti- 
ficial shade might be useful in the treatment of such diseases, whether 
the attacking fungus be identical with that observed in the above in- 
stances or a related one. 

It is certain, from the promptness with which dead animal matter 
becomes the prey of saprophytic growths, that the spores of these 
water-molds a.re well disseminated throughout fresh waters, everywhere 
ready to seize upon an opportunity for germination and growth, and 
that as a general rule these spores are quite unable to seize upon any 
animal substance which is not already dead or in a diseased condition. 

A growth of Saprolegfiia ferax once established on the body of a 
salmon is able to extend itself upon and into the living tissues around 
it, which it seizes upon and destroys. Growing upon a dead ^^^^ it not 
only ensnares the neighboring living eggs, but sometimes pierces their 
shells and establishes itself on the internal i)arts. In one instance the 
fungus had gone so far as to attach itself to a living embryo, which, on 
removal from the shell, was found to supi^ort on the sac quite a tuft of 
growing fungus, though neither on the sac nor any other part of the 
fish was a trace of dead substance discernible. 

It has been ascei-tained that the Saprolegnia which attacked the 
living salmon can be communicated by contact to dead flies, and that 
Saprolegnia found growing in the ordinary way on dead flies in water 
can be communicated in its turn to living and healthy dace and may 
so flourish on them as to cause their death. 

The impression has prevailed that the Saprolegnia which infests the 
eggs in hatching-troughs originates in or is encouraged by bare wood 
exposed to water, and that special effort is necessary to prevent its 
forming; but experience at this station does not show that attacks of 
fungus on either eggs or fish could be traced to bare wood, and, on the 
other hand, eggs and fish in troughs carefully varnished with asphaltum 
are no freer from fungoid or other disease than tliose in neighboring 
troughs from which long use had worn almost the last vestige of varnish. 



56 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The best precaution against this growth is the careful picking out of 
dead eggs before there is time for the fungus to grow on them, and in 
case of a serious attack on fry or older fish to treat them with an exterior 
application of salt, which, while not a cure-all, is very efficacious in 
cases of fungous diseases, and, if prudently used, a safe remedy for fish 
that have reached the feeding stage. 

To apply this remedy to fry in the troughs a saturated solution of 
salt in water is made — that is, the strongest brine that can be made with- 
out heatiug the water. The flow of water in the trough to be treated 
is then stopped, which leaves it from 3 to 4 inches deep, when enough 
brine is poured in to make the water in the trough about as salt as com- 
mon sea-water, about 1.028 specific gravity. The fish are left in this 20 
or 30 minutes, unless they exhibit uneasiness, and then fresh water is 
turned on. Precaution is taken to dilute the brine with an equal quan- 
tity of water, to distribute it the whole length of the trough, actively 
stirring the water to secure an even mixture; and before turning on the 
usual water supply a large quantity of fresh water is likewise poured 
in, distributing it the whole length of the trough and stirring as before, 
to guard against a too sudden change. 

Such precautions are especially necessary in the application of salt 
to very young fish. A large number of salmon in the sac stage was 
once destroyed by pouring in a little brine without stirrmg it; it ap- 
peared to sink to the bottom and spread out in a layer by itself among 
the fry, and all exposed to it died. 

ENEMIES OF YOUNG SALMON. 

The young salmon are subject to the attacks of many animals and 
birds, such as the mink, mole, star-nosed mole, common rat, muskrat, 
kingfisher, great horned owl, great blue heron, sandpiper, and fish- 
hawk, besides frogs and all large fishes. 

At Craig Brook the mink has caused serious loss. As a protection 
some of the ponds are covered with galvanized poultry netting, and 
traps are kept constantly set in the avenues by which this animal is 
apt to approach. The mole burrows through embankments and thus 
sometimes causes trouble. The star-nosed mole is known to steal dead 
eggs, and is suspected of taking live ones. The rat sometimes takes 
young fish from the troughs. The muskrat burrows in embankments 
and sometimes eats fish. 

The different fish-eating birds occasionally steal fish from the ponds 
or troughs, but if a careful watch is kept the danger is not great. 
Frogs may be exceedingly destructive to young salmon, and must be 
caught out of the fish-ponds. 

To avoid loss from cannibalism among the fishes it is necessary to 
feed them well and to take great care that no large fish get in among 
the small ones. 



Fish Manual. (To face page 56. 



Plate 18. 




TAKING SPAWN OF LANDLOCKED SALMON AT GRAND LAKE STREAM, MAINE. 



THE LANDLOCKED SALMON. 



The landlocked salmon was formerly regarded as specifically distinct 
from the seagoing form, but it is now generally considered only a 
variety. The fish found in Sebago Lake and other localities in the 
United States is known as Salmo solar sehago, and the Canadian form as 
Salmo salar ouananiche. From the fish-culturist's ]>oint of view, how- 
ever, the marked difference between the landlocked and the seagoing 
salmon in habits and growth must separate them as widely as any two 
species of the same family. 

Landlocked salmon are known to exist only in some of the lakes in 
Sweden, besides the lakes of eastern North America. They are native 
to most of the lakes of eastern Labrador, including the waters tribu- 
tary to Ungava Bay, and find their western limit in Lake St. John and 
vicinity, on the Saguenay Kiver. Those of the latter district have been 
much written about under the name of ^^ ouananiche." 

Doubtless the absence of the seagoing instinct is at the bottom of 
most of the variations from the normal type of Salmo salar which the 
landlocked salmon exhibits. Its lower tone of color, less Y)ermanent 
sexual marks, and greater liability to ovarian disease, as well as diflfer- 
ent habits of feeding, may perhaps be referab""" to the same general 
cause. There are some other peculiarities, however, which are not so 
easily explained. For instance, the eggs of the landlocked salmon are 
considerably larger thau those of the sea salmon, and the very young 
fry are correspondingly larger. 

The growth of the young of the Sebago landlocked salmon seems to 
be more rapid than that of the anadromoiis salmon, for some specimens 
more than a foot long still bear on their sides dark, transverse bands, 
characteristic of young salmon; but it may be that the landlocked fish 
simply retain the marks of the immature stages to a later period of life. 
This view is supported by the fact that the dark bands are never com- 
pletely obliterated from the sides of the landlocked salmon, being always 
very distinct, even in adult specimens, on the under side of the skin, a 
character absent among migratory salmon. 

The landlocked salmon is smaller than the anadromous saln-on, but 
its tiesh is fat and rich and of a very delicate flavor. In game qualities 
it is, for its size, quite the peer of the larger salmon, and afJbrds keen 
sport to the fly fisherman. It is, therefore, much sought after, and 
ranks in public favor among the foremost fresh-water species. 

57 



68 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The natural range of tlie landlocked salmon in the United States is 
much restricted. Leaving out of the question the salmon formerly 
frequenting the rivers tributary to Lakes Ontario and Champlain, the 
extent of whose migration is a matter of doubt, we find them only in 
four limited districts, all in the State of Maine, namely, the Presumpscot 
River (including Sebago Lake) in Cumberland and Oxford counties, the 
Sebec River (a tributary of the Penobscot) in Piscataquis County, the 
Union River in Hancock County, and the St. Croix River in Washing- 
ton County. There are some minor differences between the fisli of these 
several districts, of which, perhaps, that of size is most notable. The 
Sebago and Union River fish are much larger on the average than those 
of the Sebec and St. Croix. The Sebago salmon average at tlie spawn- 
ing season 4 or 5 pounds weight for the males and a pound less for the 
females, while specimens of 12 and 14 pounds weight are not rare, and 
there is a record of one of 25 pounds. The Union River fish are about 
the p.ame size. The St. Croix fish vary in the matter of weight in dif- 
ferent parts of their range, but the average weight of either sex at 
Grand Lake Stream is a little less than 3 pounds; specimens of over 6 
pounds are rare, and none is on record of over 10 pounds. 

After attempts to collect eggs of landlocked salmon in each of the 
four regions mentioned, it was found that Grand Lake Stream in the 
St. Croix district afforded excellent facilities for this work. A hatching- 
station at that place was operated from 1875 to 1892, and has been 
recently reopened. 

The following notes on fish-cultural methods have special application 
to Grand Lake Stream : 

The landlocked salmon of the St. Croix, though originally well dis- 
tributed through the lakes tributary to that river and still inhabiting 
a great many of them, finds in some a much more congenial home 
than in others, its favorite abode being Grand Lake on the Schoodic 
River. This body of water is of irregular shape, about 12 miles in 
length and 4 in extreme breadth, fed almost wholly by short streams 
that form the outlets of other lakes, and from this cause, as well as 
from the fact that it drains a gravelly country and is girt with clean 
rocky shores, it is one of the purest of the Maine lakes. Its greatest 
depth is believed to be little more than 100 feet. Its outlet is Grand 
Lake Stream, a shallow, rapid, gravelly stream, about 3 miles long, to 
which the salmon go in October and Kovember to deposit their eggs. 
Comparatively few of the salmon of this lake resort to the streams 
tributary to it. 

The operations with landlocked salmon necessarily differ from those 
with migratory salmon. Being at home in fresh water and having there 
their feeding-grounds, they continue to feed until the close approach 
of the spawning time, and hence they could not be penned up in the 
summer without some provision for an artificial supply of food, which 
would probably involve a great deal of expense and trouble. More- 



MANUAL OF FISH-CULTURE. 59 

over, the necessity of collecting breeding fish early in the summer does 
not exist, because they are at no time more congregated and easy to 
catch than at the spawning season. 

Their capture is easily effected by stretching a net across the outlet 
of the lake and leading them through a tunnel-formed passage into an 
inclosure of netting. There happens to be at this point a wide surface 
of smooth bottom, with water from 1 to 3 feet in depth, affording an 
excellent site for si)acious iiudosures, not only for entrapping but for 
assorting and storing salmon during the spawning season. Nets are 
generally stretched across the stream (to keep the fish back in the lake) 
immediately after the beginning of the close season, September 15. 
The earliest of them begin to spawn before the end of October, but the 
actual inclosing of the breeding stock is deferred until the early days 
of November. The taking of spawn generally begins about November 
6 and continues two or three weeks. Commonly by November 20 or 22 
this work is completed, and the breeders are carried a mile or two up 
the lake and liberated. 

The method of manipulation is the same as at the Craig Brook station, 
and does not differ materially from that adopted by all the American 
breeders of Salmonidce. The results in the impregnation of the spawn 
are not so uniformly satisfactory as with sea salmon. Ovarian dis- 
ease seems more prevalent among landlocked than among migratory 
salmon. The occurrence of white eggs among the normally colored 
and healthy ones, as they are yielded by these fish, is very common, 
and occasionally the entire litter is defective. It is not improbable 
that some eggs are incapable of impregnation, though exhibiting no 
visible signs of disease. However, the general result is satisfactory, 
the ratio of impregnated eggs being from 93 to 95 per cent. 

The facilities for developing and hatching the eggs at Grand Lake 
Stream are rather poor. No good site could be found by the side of 
the stream, no suitable brook could be found near enough to the fishing- 
grounds, and the neighboring springs lacked either volume or facilities 
for utilization. Of three hatcheries, two use spring water exclusively, 
and one of them lake or stream water exclusively. The lake water is 
preferred, but unfortunately it can only be used for the slow develop- 
ment of part of the eggs, circumstances connected with the floating of 
timber down the stream compelling the evacuation of that hatchery in 
March. The main hatchery is well located except that the water is from 
springs, and this unfavorable circumstance is well counterbalanced by 
the facilities for aeration, which are very good and very fully employed. 
The eggs are placed upon wire-cloth trays in stacks or tiers, ten deep, 
and arranged for a free horizontal movement in the water. 

The egg shipments are made in January, February, and March, and 
sometimes in April. The eggs hatched are selected from those that have 
been retarded in development; the fry reach the age for liberation in 
Jane, when their natural food is believed to be abundant. 



60 REPORT OP COMMISSIONER OP FISH AND FISHERIES. 

Experience at Green Lake has supplied some interesting data. Here 
we find tlie breeding- grounds of the salmon both in the affluents and in 
the effluent of the lake, but, unlike Grand Lake, mainly in the affluents. 
Great Brook, the largest tributary, is most resorted to, and on this 
stream is located a station for the propagation of this species. The 
most of the breeders are taken in a trap in the brook, which they 
readily enter when seeking to ascend to their natural breeding-grounds 
just above. The trap is constructed of wood, and close to it, also in the 
bed of the brook, are numerous pens of the same material, in which the 
fish are assorted and held during the spawning season. On the bank, 
snug by the pens, is the spawn-house, and a few rods away is the 
hatchery. The hatchery is supplied with water from Rocky Pond, the 
source of Great Brook, by a wooden flume 7,050 feet long, supported by 
wooden trestles, at some points elevated many feet above the ground. 
In cold weather the water cools off 1| degrees in passing down this 
flume; in warm weutlier it warms up Ih degrees. Though the summer 
temperature during the early years of the station was sometimes over 
80° F. and some other species succumbed to the heat, the landlocked 
salmon endured it safely, and the only notable effect on them was that 
at 75° and upward the adults reared in the station ponds refused to eat. 

As at Grand Lake Stream, among the adult wild salmon caught for 
breeding each year are many more females than males. In 1889 the 
proportion was 3 females to 2 males; in 1893 it was 9 to 4. The size of 
the Green Lake salmon is remarkable; the mean of 69 full-roed females 
in 1889 was 7.8 pounds in weight and 25.5 inches in length; the males 
the same year averaged 5 pounds in weight and 22.3 inches in length; 
one female weighed 11 pounds 9 ounces, and measured 30 inches; 
another, 11 i^ounds G ounces in weight, was 30^ inches in length; one 
male, 3 L inches long, weighed 13 pounds 8 ounces. The number of eggs 
yielded by the females is about 4,000 each. 



Fish Manual. (To face page 61 .) 



Plate 19. 





-' "- 


1 




THE RAINBOW TROUT. 



DESCRIPTION OF THE FISH. 

The body of the rainbow trout {Salmo irideus) is comparatively short 
and deep, and is more elongate in males than in females. The average 
depth is contained about three and four- fifths times in the body length. 
The short head, which is obtusely ridged above, is about one-fourth the 
total length. The mouth is smaller than in other species of Sahno, the 
maxillary reaching scarcely beyond the eye, which is rather large, and 
is contained five times in the side of the head. The caudal fin is dis- 
tinctly but not strongly forked. On the vomer are two irregular series 
of teeth. The dorsal rays number 11 and the anal 10. In the typical 
species there are about 135 scales in the lateral series, with 20 rows 
above and 20 below the lateral line; in the several subspecies the 
number of rows of scales along the side is from 120 to 180. The color is 
variable, depending on sex, age, and character of water. Typical adult 
fish are bluish above, silvery on the sides, profusely and irregularly 
dark-spotted on the back and sides, the spots extending to the vertical 
fins, with a red lateral band and blotches and a nearly plain belly. The 
sea-run fish are nearly plain silvery. The chief distinguishing color 
characteristics of the varieties are in the number and position of the 
spots. 

RANGE AND VARIATION. 

The rainbow trout is not indigenous to eastern waters, its original 
habitat being the Pacific coast of the United States. It is especially 
abundant in the mountain streams of California. A few specimens, 
however, have been taken in salt water, and it is not unlikely that some 
find their way through the rivers into the sea. 

The species is subject to considerable variation in form and color in 
difierent parts of its range, and the following varieties have received 
recognition by ichthyologists: The brook trout of western Oregon and 
Washington {Salmo irideus inasoni), which rarely weighs as much as a 
pound and is locally abundant in the streams of the Coast Eangefrom 
Puget Sound to southern Oregon 5 the McCloud River trout ( Salmo 
irideus Shasta), which attains a large size, is abundant in the streams of 
the Sierra Nevada Mountains from Mount Shasta southward, and is the 
rainbow trout which has received most attention from fish-culturists; 
the Kern River trout (Salmo irideus gilherti), which attains a weight of 
8 pounds and is found only in Kern River, California ; the noshee or 
nissuee trout {Salmo irideus stoiiei), which inhabits the Sacramento 
basin and reaches a weight of 12 pounds; the golden trout of Mount 
Whitney {Salmo irideus aqua-honita), which inhabits streams on both 
sides of Mount Whitney, California. 

61 



62 REPORT OF COMMISSIONER OF FISH A.ND FISHERIES. 

Ill the extensive section of the West in whicli the fish abounds its 
name varies in different localities; red sides, mountain trout, brook 
trout, and golden trout, besides rainbow trout, are some of the popular 
appellations, while in the States east of the Mississippi Eiver it is verv 
generally called rainbow trout or California trout. 

TRANSPLANTING. 

The rainbow trout has been successfully transplanted in many of the 
mountain streams in different parts of the United States, where it 
grows and multiplies rapidly, as is shown by the many favorable 
reports. The best results, however, seem to have been obtained from 
plants made in streams of Michigan, Missouri, Arkansas, throughout 
the Alleghany Mountain ranges, and in Colorado, Nevada, and other 
Western States. It was introduced into eastern waters by the United 
States Fish Commission in 1880, but it is possible that specimens of it, 
or its spawn, had been brought east prior to that time by some of the 
-State commissions or by private enterprise. 

It is believed that this species will serve for stocking streams for- 
merly inhabited by the brook trout {SalveUnus fontinalis), in which the 
latter no longer thrives, owing to the clearing of the lands at the 
sources of the streams, which has produced changed conditions in and 
along the waters not agreeable to the brook trout's wild nature. The 
rainbow is adapted to warmer and deeper waters, and is therefore 
suited to many of the now depleted streams which How from the moun- 
tains through the cultivated lands of the valleys. 

Rainbow trout differ widely from brook trout and other pugnacious 
fishes, in that they feed principally upon worms, larviP, Crustacea, and 
the like, and do not take readily to minnows as food. They should be 
planted in spring or early summer, when their natural food is abundant, 
as they will then grow more rapidly and become accustomed to life in 
the stream, and when worms, larvae, etc., are no longer to be found, 
their experience and size will enable them to take a minnow or any- 
thing that may present itself in the shape of food. 

Fry should not be i)lanted in open waters until they are several 
months old, and then not until the temperature of the streams begins 
to rise; but fish hatched in December and January can safely be planted 
in April and Ma>. 

SIZE AND GROWTH. 

The size of the rainbow trout depends upon its surroundings, the 
volume and temi)erature of the water, and the amount of food it con- 
tains. The average weiglit of those caught from streams in the East is 
probably less than a pound, but some weighing 03 pounds have been 
taken. In the Ozark region of Missouri they are caught weighing 5 to 
10 pounds. In some of the cold mountain streams of Colorado their 
average weight is not more than G or 8 ounces, but in lakes in the 
same State, where the water becomes moderately warm in summer 
and food is plentiful, they reach 12 or 13 pounds, lish of this size being 
from 25 to 28 inches long. In the Au Sable liiver, in Michigan, they 



Fish Manual. (To face page 62. 



Plate 20. 




MANUAL OF FISH-CULTURE. 63 

attain a weight of 5 to 7 pounds. In their native streams of California 
they are often caught ranging from 3 to 10 pounds, but average from 
1 to 2 pounds. The hirgest specimen ever produced in the ponds at 
Wytheville, and fed artificially, weighed 6J pounds, but many others in 
the same ponds weigh from 1 to 3 pounds. 

The average growtli of the rainbow trout under favorable artificial 
circumstances is as follows: One year old, from ^ to 1 ounce; 2 years 
old, from 8 to 10 ounces; 3 years old, from 1 to 2 pounds; 4 years old, 
from 2 to 3 pounds. They grow until they are 8 or 10 years old, the 
rate diminishing with age. Some grow much faster than others under 
the same circumstances, but the rate of growth is largely a question of 
food, temperature of water, and extent of the range. In water at 60°, 
with plenty of food, fish 1 or 2 years old will double their size several 
times in a single season ; while in water at 40°, with limited food, the 
growth is scarcely perceptible. 

The rainbow, like the brook trout, will live in water with a compara- 
tively high temperature if it is plentiful and running with a strong 
current, but sluggish and shallow water, even with a temperature of 
70° F., is dangerous for brook trout. Rainbow trout will live in warmer 
water than brook trout, and are found in swift, rapid streams at 85o F., 
especially where there is some shade, but in ponds that temperature is 
dangerous even with shade and a good current. In its natural condi- 
tion this trout is usually found in water varying from 38° F. in winter 
to 70° F. in summer, and in selecting a site for a trotit hatchery spring 
water with a temperature of 42° to 58° is required. 

The rainbow trout is a superior game fish, a vigorous biter, and fights 
bravely for liberty, though in the East it is somewhat inferior to the 
brook trout in these respects. 

In the following pages is described the manner in which this fish is 
propagated artificially at Wytheville, together with the design and con- 
struction of the ponds and apparatus, and such other information is 
given as is suggested by experience at this station. It may be observed 
that the methods would be equally applicable to the propagation of the 
brook trout. 

Sr AWNING-PONDS. 

In constructing ponds, one of the first considerations is to place the 
fish absolutely under the control of the fish-culturist, that he may be 
able to handle them without delay or inconvenience. At Wytheville 
they are constructed entirely of wood, about 15 by 50 feet and 3 to 3J 
feet deep, and shaped as shown in plate 21, and have been found very 
satisfactory. Excellent water circulation is obtained in all jiarts, and 
there are no corners for refuse to lodge in. The bottom of the pond is 
built with a gradual elevation, in the direction of the upper end, of 2 
inches in the entire length of the pond. This makes it practically self- 
cleaning; nearly all of the foul matter will pass oflf" and any remainder 
can be disposed of by diawing the water down low for a short period 
and then flushing the pond with fresh water. This method obviates the 
necessity of handling the fish, which is very important, especially when 
near the spawning time. 



64 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

A guard-rack made of thin, narrow slats is arranged on an incline of 
about 45°, as shown at C. If the water is to be used again in ponds 
below, a receiver is built underneath the bottom of the pond at the 
lower end, between the foot of the guard-rack and the dam-boards, 
and the floor of the pond immediately over the receiver is cut away and 
fitted with a grating. This allows matter to fall through the receiver 
and from there it is washed through the sluiceway, which taps the 
receiver by drawing the gate shown at D. The sluiceway, E, is 
covered and leads off to a general waste-ditch. 

The pond is provided with a spawning-race about a foot deep, 4 feet 
wide, and 25 feet long, placed at the upper end of the pond, as shown 
at H. Three division boards (shown at F), about 12 feet long and of 
suitable width to come within 1 or 2 inches of the surface of the water 
when the pond is filled, are firmly fixed at the bottom. The object of 
these boards is to form four avenues leading to the raceway, so that 
one or two pugnacious fish can not command the approach and keep 
back spawning fish inclined to enter. There is a dam across the race- 
way about 4 inches high (shown at G) for the purpose of bringing the 
water to that depth in the lower end, so that when the trout enter they 
will find sufficient water in which to swim freely, and not be inclined 
through fear to return to the pond. 

The water in the pond is of sufficient depth to bring its surface 
within 6 inches of the top of the dam in the raceway, which will give 
the fish, in entering the raceway, a jump of 7 inches, allowing 1 inch 
for the depth of water on the dam in the raceway. This distance has 
been found more satisfactory than any other, and spawning fish alone 
will go up. If a jump of less than 7 inches is given, other fish can 
enter the raceway without much exertion, and will ascend and disturb 
the breeding fish, which, when spawning, should be kept strictly by 
themselves. 

There is no rule regarding the supply of water that applies to a 
spawning-pond at all times and in all places. It Is necessarily gov- 
erned by the temperature of the water, size and shape of the pond, 
size of the fish to be supported, the amount of shade, etc. For a 
pond such as has been described, where water is plentiful, at least 200 
gallons per minute should be provided, with not less than 75 gallons 
per minute as a minimum, even where the temperature is from 50 to 
55 degrees and all other conditions are favorable. While the former 
amount is not absolutely necessary for the support of the fish, it 
insures the pond being kept clean and the fish are more inclined to 
enter the raceway at spawning time. In order to maintain an even 
temperature in the pond the earth is banked against the sides and 
ends, covering the framework shown on plate 21, and the embankments 
are made broad enough on top to admit of a good footway around the 
ponds. 

Such a pond as this can accommodate from 1,000 to 1,500 breeding 
fish. Fish must not be overcrowded, and in estimating the capacity of 



Fish Manual. I To face page 64.) 



Plate 21, 




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MANUAL OF FISH-CULTURE. 65 

a pond several modifying conditions must be considered, sucli as the 
size of the fish, water supply, temperature, and shade. In stocking the 
spawning- pond a good proportion is two females to one male. The 
breeding stock is selected carefully every year; only sound and perfect 
fish are retained for the next season, and the blind and emaciated 
fish of both sexes are destroyed. 

TAKING THE SPAWN. 

The spawning season varies with the locality and the temperature of 
the water. It is usually two to four weeks later in the streams than 
where the fish are kept confined in spring water. In the ponds at 
Wytheville the spawning fish may be found any time after the 1st of 
November; the season is well started by November 15, and generally 
closes about the 1st of March. December and January are the best 
months. In California the season extends from the 1st of February to 
May, and in Colorado begins early in May and continues until July. 

The natural nests of these fish are made on gravelly bottoms, and 
are round or elongated depressions about the size of a dinner x)late. 
After the eggs have been deposited and fertilized they drop between 
the pebbles of the nest, where they lie protected until hatched. 

Where spawning-ponds are provided with suitable raceways the fish 
will ascend from the ponds into them, seeking a place to make their 
nests, and may then be taken out and stripped of their spawn. To take 
the fish from the raceway, a square net (I, plate 21) is dropped in on 
the cleats nailed against the side walls in the approach, shown at J, the 
dam in the mouth of the raceway is raised, and the fish driven back 
into the net. The net is then lifted out of the water, and if it contains 
too many fish to handle conveniently a landing-net is used to take out 
part of them before the square net is moved. The ripe fish are then 
placed in tubs or other vessels provided for the purpose. If too many 
fish are put in the tub at one time they become restless and sick before 
they can be stripped of their spawn. 

There are two methods of taking and impregnating the spawn of 
fishes, the "wet" and the "dry" methods. By the "wet" method the 
eggs a-e taken in a pan containing sufficient water to cover them and 
allow them to mix fre?ly with the milt, which is immediately added. 
After the contents of the pan have been stirred for a few seconds with 
.i feather, the eggs are set aside and left undisturbed during fertiliza- 
tion. The "dry" or "Russian" method is nowin general use; the eggs 
and milt are taken in a moist pan and it makes little difference which 
is taken first, but one should immediately follow the other, and the 
contents of the pan be thoroughly mixed. 

After the eggs and milt have had time for contact, and before the 
eggs begin to adhere to the bottom of the pan, water is added to 
the depth of about an inch, the eggs being kept in gentle motion, by 
turning the pan, to prevent adhesion. After 2 or 3 minutes the milt 

F. M. 5 



66 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

is poured off and clear water is put in the pan, in which the eggs are 
allowed to remain until they separate, which will be in from 15 to 45 
minutes, depending on the temperature of the water. It is preferable 
to take the eggs to the hatchery before the milt and water are poured 
off, and there rinse them ofi' and place them directly on the hatching- 
trays (previously arranged in the troughs) and then allow them to 
separate. In freezing weather it is advisable to strip the eggs in water 
or to use two pans, one set in the other, with water in the bottom pan 
to prevent the eggs from being chilled. 

In taking spawn the manipulation of the fish without injury is a very 
delicate and exacting task, full knowledge of which can only be 
acquired by experience, as it is difficult to squeeze the spawn from the 
fish without injuring or even killing it. In taking hold of the fish in 
the spawning-tub the operator catches it by the head with the right 
hand, the back of the hand being up, and at the same time slips the 
left hand under the fish and grasps it near the tail, between the anal 
and caudal fins. A fish caught in this way can be easily turned over 
as it is brought out of the water, so that its abdomen is uji and in the 
proper i)osition for spawning by the time the spawning-pan is reached. 
If the fish struggles it must be held firmly, but gently, until it becomes 
quiet, and when held in the right position it will struggle only for a 
moment. A large fish may be held with its head under the right arm. 

When the struggle is over the right hand is passed down the abdo- 
men of the fish until a point midway between the pectoral and ventral 
fins is reached, then with the thumb and index finger the abdomen is 
pressed gently, and at the same time the hand is slipped toward the 
vent. If the eggs are ready to be taken they will come freely and 
easily, and if they do not, the fish is put back in the pond until ready to 
spawn. If the eggs come freely from the first pressure the operation 
is repeated, beginning at or near the ventral fin. 

After the first pressure has been given, by holding the head of the 
fish higher than the tail, all of the eggs that have fallen from the 
ovaries and are ready to be expressed will fall into the abdomen, near 
the vent, so that it will not be necessary to press the fish again over 
its vital parts, the eggs having left that iwrtion of the body. All of 
the eggs that have fallen into the abdnmen below the ventral fin can 
be easily ejected without danger of injury to the fish, caused by unnec- 
essary pressure over its important organs after the eggs have left that 
part of the body. If these d'irections are judiciously and carefully fol- 
lowed but little, if any, damage will result; and, as an illustration, it 
may be mentioned that fish have been kept for 14 years and their full 
quota of egiis extracted each season during the egg-producing term, 
which is normally from 10 to 12 years. The male fish is to be treated 
very much in the same manner as the female, except the milt must not 
be forced out, only that which comes freely being taken. 

After stripping, the fish are not returned to the spawning pond, but 
silent females are placed in one pond and the males in another. The 



Fish Manual. (To face page 66.) 



Plate 22. 




MANUAL OF FISH-CULTURE. 67 

in. lies are very pugnacious at this seasou, and sometimes fight for an 
hour or more at a time, until they are entirely exhausted; they run at 
each other with open mouths, lock their jaws together, and in that 
position sink to the bottom of the pond, where they lie for a short time, 
each holding the other in his grasp until rested, when they rise and 
resume the combat. As their teeth are abnormally long, they scar 
each other and even bite pieces of skin and flesh from the sides of their 
antagonists. 

The males are good breeders at two years old, but very few females 
produce eggs until the third season, when they are from 30 to 3G mouths 
old. At Wytheville hatchery about 1 per cent of the females spawn at 
2 years of age; about AO per cent at 3 years, and about 85 percent 
each season after that. About 15 per cent of the fully matured females 
are barren each season. It was at one time thought that the same 
individuals were barren each year, but experience' has shown that 
such is not the case, as fish which were barren one season have been 
held over, in a separate pond, until the following year, when a large 
portion, if not all, produced eggs. This sterility may be the result of 
injuries which were received the previous season, during the progress 
of spawniug. 

EGGS. 

The number of eggs produced in a single season depends upon the 
size and age of the fish. The maximum from one 3 years old, weighing 
J to 1^ pounds, is from 500 to 800; from one 6 years old, weighing 2 to 4 
pounds, it is 2,500 to 3,000. The eggs vary in size from 4i to 5 eggs to 
the linear inch, and are of a rich cream color when first taken, clianging 
to a pink or flesh color before hatching. 

THE HATCHING-TROUGHS AND TRAYS. 

The eggs are incubated on trays ])laced in troughs of various sizes and 
shapes, which at Wytheville are set in pairs, as shown on page 68. 
They are made of the best pine lumber, dressed to 1^ inches thick, and 
are 15 feet long, 14 inches wide, and 8 inches deep. Fourteen inches 
from the lower end inside is a guard-screen of perforated tin or wire 
mesh, fastened on a frame exactly fitted across the trough. Tin with 
perforations of -^ inch for very young fry, and larger ones as the fish 
grow, is preferable to wire. The screen is arranged to slide vertically 
between beveled cleats, that it may be kept clean easier. A plain 
board, 3^ inches wide, is placed 4 or 5 inches from the lower end of the 
trough to serve as a dam. 

In the upper end of the tiough horizontal screens (B, page 68), made 
of perforated tin, are used. These are so constructed that they can be 
slipped forward or raised up (as shown in the illustration) in feeding 
the fry or cleaning the troughs, and the water falling on a small wooden 
block in the center of the screen is thoroughly aerated before entering 
the trough. This arrangement possesses many advantages over the old 
method, where the screens were vertical, or nearly so, as it permits the 



68 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



fish to ascend to the head of the trough and receive the water as it falls 
from the screen, which is very beneficial. Its use not only keeps the fry 
clean even in muddy water, but also reduces the loss of fry from suffo- 
cation in the early stages, caused by their banking around tlie vertical 
screens, and obviates the necessity for trongh covers to prevent jumping, 
as trout rarely jump where the horizontal screea has been adopted. 




1 



LONGITUDINAL SECTION OF HATCtiINQ TROUGH.SHOVHINS POSITION OF HATCHING TRAYS, DAM, £TC. 



lliitcliiiig-troughs, tiuard-screeii, etc. 

Hatching-trays (C), made about twice as long as wide, i. e., 28 by 
13^, are convenient to handle and adjust in the troughs. The sides 
of the frame are made of good pine lumber, dressed, 1 inch square; 
the ends are dressed A by 1 inch, and are cut into the sides to form a 
smooth surface on the bottom for the wire filling. The wire used on 
the trays is woven with 8 threads to the inch, with a mesh \ inch long, 
and should be well galvanized after it is woven, in order to prevent 
rusting at tlie laps. 



MANUAL OF FISH-CULTURE. 69 

Four hatching-trays are placed in each trough and are secured by 
keys or wedges, and shouhl be from 1 to 2 inches lower at the end next 
to the head of the trough, as shown at U, D, D, D, page 68. If placed 
in this way, each tray will hold from 12,000 to 15,000 eggs with safety. 
Muddy water during the hatching season necessitates the use of a tin 
tray with a perforated bottom (shown at E, page 68), which is 13f inches 
wide and 32 inches long. This sets inside of the hatching-trough on 
feet raising it an inch above the bottom of the trough. The hatching- 
tray containing the eggs is placed inside and rests on the brackets 
shown at G. The fish, as they hatch out, fall i'rom the hatching-tray 
upon the perforated bottom of the tin tray, and by their movements 
work the sediment through, leaving them on a clean bottom and in no 
danger of being smothered. The tin trays are also useful in counting 
fish, or in holding small lots of fish of different species in the same 
trough. Where supplementary trays are not used, the fry fall directly 
into the troughs. 

Troughs 15 feet long will admit of four hatching-trays in a single 
row, each of which will safely carry 12,500 eggs, making 50,000 to a 
trough; this is enough to work easily, but if it is necessary to make 
more room a double row of trays may be put in, one tray resting on 
the top of the other. Thus the trough could contain 100,000 eggs as 
its full capacity. The troughs will carry this number up to the time 
of hatching by placing the trays lower at one end than the other, as 
previously described. 

When the hatching stage arrives, two trays of 12,500 eggs each are 
as many as should be left in one trough ; with this number, by using the 
horizontal sliding-screen in the upper end, there is but little danger of 
the alevins congregating and smothering in any part of the trough. If 
it is necessary to hatch a much larger number than this in one trough, 
the sliding-screen is so arranged that the water falls well up against 
the end of the trough. This is done by raising the screen and turning 
it back against the reservoir, or by putting in a wedge shaped block for 
the water to fall upon, turning the thin side of the block toward the 
upper end of the trough. Fifty thousand trout have been hatched in 
one trough prepared in this way without loss from suffocation, but it is 
not advisable to hatch such a large number together. 

The amount of water necessary for hatching and rearing depends 
upon the temperature and the manner in which the water is applied. 
The water should receive as much aeration as possible before entering 
the compartments containing the fish and eggs. At Wytheville, where 
there is an even temperature of water of 53° in the hatchery, about the 
following quantities are used in the troughs containing fish and eggs : 

100,000 eggs during incubatiou, 12^ gallons per minute. 
100,000 fish hatching to time of feeding, SO gallons per minute. 
100,000 fish from 1 to 4 months old, 50 gallons per minute. 
100,000 tisli 4 to 6 mouths old, 100 gallons per minute. 
100,000 fish from 6 to 12 months old, 200 gallons per minute. 



70 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

These amounts are ample, and probably even half would suffice if it 
were necessary to economize in the use of water. In rearing-ponds 
more water is required, as the circulation is not so good and the out- 
door exposure causes the temperature to rise. If water is plentiful, 
double the amounts stated would be advisable for pond-culture. 

During- the last two seasons at Wytheville 80 to 85 per cent of the 
eggs taken i)rodaced fish, of which about 70 per cent were raised to 
three months old and 55 per cent to yearling fish. The loss in eggs 
was almost entirely due to failure in impregnation, very few being lost 
from other causes. 

CARE OF EGGS AND FRY. 

After the eggs are placed on the trays, the only attention necessary 
until the hatching begins is to keep them clean; the dead eggs, which 
may be known by their turning white, must be i)icked out at least once 
each day. After the eye-spot can be i^lainly seen it is well to run a 
feather through the eggs for the purpose of changing their position 
on the trays, and to disclose any foreign matter or dead eggs that 
may be hidden underneath. Tbe greatest care should be exercised in 
handling the eggs at any time, particularly from the first or second day 
after collection up to the appearance of the eye spot, and then only when 
absolutely necessary. During this period, the eggs are very delicate, 
and even x>assing a feather among them may cause a heavy loss. 

The time required for hatching depends mainly upon the temperature 
of the water. Rainbow trout eggs will hatch in water at 50° in from 42 
to 45 days, each degree colder taking 5 days longer, and each degree 
warmer 5 days less; the difference increases as the temperature falls 
and diminishes as it rises. 

After the fry hatch they require but little attention until the umbil- 
ical sac is absorbed and the time for feeding arrives. They are exam- 
ined each day, and the dead fish and decayed matter removed from 
the troughs, which are kept perfectly clean, and if possible provided 
with a thin layer of coarse white sand on the bottom, to keep the fish 
in healthy condition. As the fish grow they should be thinned out in 
the troughs, from time to time, as their size may require. When they 
first begin to feed, 12,000 to 15,000 fish to the trough are not too many; 
but by the time they get to be 1 J to 1 J inches long they must be divided 
into lots of 8,000 to 10,000 to each trough ; while with fish averaging 3 
inches in length, 3,000 to 4,000 are as many as one trough will accom- 
modate. It is advisable to give as much room as is practicable. 

REARING-PONDS. 

Ponds for rearing trout are from 8 to 12 feet wide, and of any desired 
length up to GO feet, which, for convenience in drawing them off and 
in feeding the fish, is about the extreme limit. The size, shape, and 
arrangement of the ponds must depend upon the ground on which 
they are to be constructed. If practicable, it is best to build them on a 



Fish Manual. (To face page 70.) 



Plate 23. 



P P 






•e'S 




MANUAL OF FISH-CULTURE. 71 

hillside, one above the other, with earth and piling embankments on 
the lower sides and at the ends. A pond of this kind is shown in 
plate 23, and is the one here described. Various materials may be used 
for damming the water. The embankments may be made altogether 
of earth or lined with stone, brick, cement, or timber, according to 
circumstances. Where the ground is of a porous or loose formation it 
is necessary to use piliug or cement for the inside of the embankments 
and possibly cement for the bottoms, but earth bottoms are best where 
the nature of the ground permits. The water enters the pond at one 
end and discharges from the lowest opposite corner. The bottom is 
graded as shown in the cross-section, plate 23, with a slope toward the 
outlet, so that when all the water is drawn out the fish are led into the 
receiving- trough (C), the top of which is flush with the earth bottom in 
that part of the pond. 

The outlet for the water is an L-shaped pipe, shown at F, and is 
placed in the corner of the pond, the long end passing through the 
piling and underneath the pond embankment; the short end, called 
the standpipe, stands close to the inside corner of the pond, in an 
upright position. The standpipe has two or more holes cut through 
(G) on the side next to the receiving-trough, to let the water pass out 
in drawing down the pond. The size of these holes is in proportion to 
the size of the standpipe, which, in turn, is governed by the size of the 
pond. The holes may have blocks of suitable size tacked over them to 
allow the pond to fill with water, or, what is more convenient, covered 
with blocks arranged to slip down in grooves, one block resting on the 
other. Surrounding the standpipe is a crib, the front of which is 15 
inches or more from the pipe and contains an opening for a guard - 
screen, which is 11 to 16 inches wide and made with copper or galva- 
nized wire cloth, the size of the mesh depending on the size of the fish 
in the pond. In the bottom of the pond is a receiving-trough (G) for the 
fish, built in proportion to the size of the pond ; 10 feet long, 16 inches 
wide, and 6 inches deep is a satisfactory size for a pond like the one 
described. This trough extends to and connects with the standpipe, 
and the guard-screen is arranged to fit down on the inside. Every 
part is made secure, to prevent fish from escaping when drawing off the 
water. The supply-trough or jiipe is arranged to keep the fish from 
jumping into it from the pond, as shown at A. 

STOCKING THE REARING-PONDS. 

The rearing-ponds at Wytheville are stocked gradually, 500 to 1,000 
fish being placed in the pond and trained to take food before more are 
added, as that number can generally find enough natural food to sub- 
sist upon until they learn to take artificial food. When they have been 
accustomed to hand-feeding another 1,000 fish are added, and in about 
ten days 2,000 more, this practice being continued until the pond is 
stocked with the desired number. When fish are first released in ponds 



72 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

they are wild and run away from the food given them ; hence the neces- 
sity of teaching a few fish to eat before more are added. The number 
of fish that a pond of a given size can support depends upon the amount 
of water and shade and the temperature of the former. Ten thousand 
fish are ample for a pond 10 by 50 feet, with water deepening from 3 
inches to 3 feet. 

FOOD FOR FRY. 

Beef or sheep liver, ground or chopped to a pulp, seems to be the 
most satisfactory artificial food for young trout. Fresh, hard-boiled 
eggs, grated fine, are good, but expensive. Efforts have been made to 
produce a natural or living food, such as insect larvae and small crus- 
taceans, and this may yet be accomplished for late spring and summer 
feeding, but for feeding the fry during the first three or four months of 
their lives, which is in the winter season, there is nothing better than 
liver. Shad and herring roe, put up in sealed tin cans, have been used 
to a limited extent with satisfactory results, and it is believed that they 
will furnish a wholesome and natural diet. 

The manner of feeding young fry is very important, as the losses from 
improper feeding are greater than from all other causes combined. If 
there is undue haste the water becomes polluted, or the food is so 
distributed that some fish are prevented from getting their proper share. 
Polluted water is very injurious to the young fish, being apt to produce 
intiammation of the gills and a slimy, itching condition of the skin, 
which often causes heavy mortality. 

The fry are ready to take food as soon as the sac is absorbed, the 
time required for this depending upon the growth of the fish, which is 
governed by the temperature of the water. Where the temperature is 
regular at 53^ they will take food in about 30 days after hatching, and 
the time to commence feeding may be closely determined by watching 
the movements of the fish. Before the sac is entirely absorbed they 
will begin to break up the school on the bottom of the trough and 
scatter through the water, rising higher and higher from the bottom 
each day, until they can balance themselves gracefully in a horizontal 
position, all heading against the current and swimming well up in the 
water. By dropping some small bits of cork or the nap from red flannel 
on the surface of the water it can be determined if they are ready for 
food; if they strike at the pieces as the current carries them down it 
is evident they are hungry. 

The liver is prepared by chopping it very fine and, if necessary, 
mixing it with water, in order that it may be distributed evenly. It 
should be given to the fish by dipping a feather into the liver and 
gently skimming it over the surface of the water. After the fish grow 
to be 1^ to 1^ inches long they begin to take up the food that settles 
on the bottom of the trough; it is then not necessary to mix the food 
with water, and it can be given by hand. The young fry are fed five 
or sis times a day aud the food given slowly and sparingly. After they 



Fish Manual. (To face page 72.) 



Plate 24. 




MANUAL OF FISH-CULTURE. 73 

learn to take their food from the bottom of the trough it is necessary 
to feed them only three times daily, but more food must be given at 
each meal. 

FOOD OF ADULT FISH AND YEARLINGS. 

In domestication the rainbow trout is preferably fed upon a meat 
diet altogether, if it can be had plentifully and sufficiently cheap; 
otherwise a mixture of liver and mush may be used advantageously. 
The mush is made by stirring wheat shorts or middlings in boiliog 
water until the mixture becomes thick; it will keep for several days, 
even in warm weather, if put in a cool place. The liver is ground 
or chopped fine and mixed thoroughly with the mush in any desired 
proportion up to four fifths of the whole, but it is better to mix 
only as needed. This mixture has been used satisfactorily for many 
years. 

A meat-chopper may be obtained for grinding liver which will do the 
work in an excellent manner, leaving no strings or gristly chunks to 
choke the fish. There are several sizes of the machine made, with extra 
perforated plates having different- si zed holes, from one-twelfth to one- 
fourth of an inch in diameter, so that the meat may be prepared coarse 
or fine, to suit the size of the fish to be fed. For small fry it is neces- 
sary to use the plate having the smallest holes and to grind the food 
over several times until fine enough to use. 

The practice of throwing food into the pond in handfuls causes the 
fish to come together in great numbers and in a violent manner; and 
struggling with open mouths to get a bite of the food, they often hurt 
each other, injure one another's eyes, sometimes even plucking them 
from the sockets. This is probably one of the main causes of blindness 
among pond-fed fish. 

The most approved method of feeding is to walk along the pond its 
entire length to the upper end (the fish will soon learn to follow to that 
point), then scatter a handful of food along the surface of the pond so 
that it will fall to pieces. The fish follow and take up what has been 
thrown out and then return to watch for the next handful, and the 
operation is repeated until sufficient food is given. This manner of 
feeding induces all the fish to head in the same direction while eating, 
thus reducing the danger of injury. 

The amount of food for a given number of trout depends upon the 
size of the fish and the temperature of the water, as fish will not take 
food as freely in water of a low temperature as in warmer water. With 
water from 50° to 60° a daily ration for 1,000 yearling fish ranging 
from 3 to 5 inches in length is about ^ of a pound; while for the same 
number, 8 to 12 inches long, about 12 pounds per day are required. 

As the fish increase in size the amount of food should be increased 
proportionately. They are fed twice a day at regular hours, morning 
and evening, giving half of the daily allowance each time. This keeps 
^hem in a thrifty and growing condition. 



74 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 








I 






i^i^<^>'^a«'^irui^^>f£,^^ 










,^^ 



■7--- 






!U^^^ 






I 






I 







Cross-section through Box after it has been packed and closed. 



PACKING EGGS FOR SHIPMENT. 

In packing trout eggs for shipment they are usually placed on trays 
and packed in wet moss and the eggs divided into from five to ten equal 
parts, according to the size of the shipment, using trays of suitable 
size to hold each part. If 30,000 eggs are to be shipped, ten trays are 
used large enough to contain 3,000 eggs each; if 15,000 eggs, ten trays 




A. Egg-tray. 



B. Foundation-board. 



containing 1,500 eggs each ; 10,000 eggs, eight trays of 1,250 each, etc., 
and if over 30,000 eggs are to be shipped the shipment is made in 
more than one lot. In a i^ackage of more than ten trays, especially if 
the trays are large, the eggs on the lower trays are liable to be crushed 



MANUAL OF FISH-CULTURE. 



75 




C. Ice-hopper. 



by the weight above, and if less than five trays are used in a shipment 
the package is liable to become dry, and the eggs reach their destina- 
tion either dead or in a shriveled condition. 

The frames of the trays are made of light, soft wood dressed to | by 
^ of an inch, with a soft canton-flannel bottom tightly stretched and 
well tacked on. The trays 
are made large enough to 
contain their proportion 
of the eggs, Avith an allow- 
ance of f of an inch be- 
tween the eggs and the 
frame of the tray. A foun- 
dation-board (B) is made 
with the same outside di- 
mensions as the tray, with 
a strip nailed around the 
edge on the upper side to 
form a cushion of moss 
for the bottom tray. A 
hopper for ice (C) is used 
on the top tray. The out- 
side case (E) is made 7 to 
8 inches larger on the 
sides (inside measure) 
and 5 inches deeper than 
the outside dimensions of 
all the trays after they 
are cleated together, in- 
cluding the hopper and 
the foundation-board, as 
shown at D. 

The trays having been 
prepared, the eggs are se- 
lected, those being taken 
which show eye-spots and 
are not too old to reach 
their destination before 
the time for hatching. 
Allowance is made for 
changes in temperature 
on the road which would 
cause them to hatch too 




soon. 



D. Egg-trays packed and cleated. 



The eggs are taken from the hatching-trays in pans, ^ell cleaned of 
all sediment, and given a slight concussion by allowing water to fall on 
them from a small spout or sprinkling pot, which causes the dead and 
unfertilized eggs to turn white, when they are carefully removed. The 



76 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



eggs are then accurately weighed or measured (1 ounce may be weighed 
aud counted, or the eggs lor one tray counted and then weighed) and 
the required number placed in a single layer in the middle of the tray, 
leaving an empty space all round next to the frame. 

The trays are then placed one above the other on the foundation- 
board, after each is covered with a piece of mosquito netting, which 
should be at least 2 inches larger each way than the tray, and the 




Outside case. 



tray is filled with wet moss, the part immediately over the eggs in a 
loose manner, the empty space around the eggs packed tight. This 
gives support to the next tray above and prevents the eggs from com- 
ing in contact with the wood and becoming dry and shriveled. 

After all the trays are thus arranged the hopper is placed on top and 
the whole cleated together, as shown at D. They are then ready to be 
placed in the box or outside case (E). Dry sphagnum moss is placed 



MANUAL OF FISH-CULTURE. 77 

in the boutom of the box to a depth of about 3 inches and the crate 
of trays placed as near the center of the box as possible. The sides 
are well packed to hold it firmly in position, and when the top of the 
hopper is reached with the packing it is well filled with ice, the remain- 
ing space in the box being filled with moss. Wet moss or wet packing 
of any kind should never be used for the cushion around the egg-crate, 
as it does not preserve an even temperature and is liable to freeze solid 
if exposed to a low temperature in transit. A cross-section of the 
box thus packed is shown on page 74. 

The box containing the eggs should be provided with handles to 
facilitate moving during transportation, in order that the liability to 
injury from jarring or concussion may be reduced. For a long journey 
the lid of the box is provided with hinges and hasp and staple, so that 
the ice may be easily renewed. Eggs packed as described above have 
been shipped with safety to all parts of the United States and to for- 
eign countries. 

DISEASES OF FEY AND ADULTS. 

The most common diseases of trout fry are the inflammation of their 
gills and a slimy skin disease, which may be caused by impure water; 
the food itself may produce it, especially if stale liver is used, but it 
generally follows fouling of the water while feeding. By watching 
the movements of the fish, the symptoms of disease can generally be 
detected before it reaches an alarming stage. If the gills are affected 
the fish will usually swim high in the water in an uneasy, restless man- 
ner, as if gasping for breath, and when this is observed the gills must 
be examined to see if they are becoming inflamed and swollen. If a 
skin disease is attacking the fish, they generally indicate it by rubbing 
themselves on the bottom of the trough or against anything that may 
be convenient, or by diving down and giving themselves a quick, twist- 
ing motion against the bottom of the trough. If the progress of dis- 
ease is not promptly checked, it will soon reach a stage where nothing 
can be done, and the fish grow weaker every day until they begin to 
die in alarming numbers. One of the best remedies for both diseases 
is salt sprinkled through the water after the ponds are drawn low, and 
for a bad case of skin disease a half pint of salt for every gallon of water 
in the trough is used, or about that proportion. The fish should be 
watched closely and allowed to remain in the salt water until they 
become restless and begin to turn on their sides. Then, as fresh water 
is turned on and the trough fills, a slime will arise and float on top of 
the water, like a white scum. Coarse sand should be kept in the trough 
for the fish to rub themselves against. Salt is also good for the dis- 
eased gills and will free them from adhering sediment. 

Fungus, *'blue swelling," and other diseased conditions sometimes 
occur, but the most serious diseases of the fry are those just described. 
Parasites sometimes attack the fish, but if the water is pure and the 
fish in a healthy condition, they are not troublesome. To keep the fish 



78 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

that are raised iu trouglis and tanks iu a healthy state, it is well to give 
them a salt batli occasionally, and a small quantity of salt in their food 
will at times do them good. A little sediment from the reservoir, or 
such as collects on stones in the streams, is beneficial to fish if mixed 
with their food. It seems proper that they should have something of 
this nature, since all or nearly all of their natural food contains more 
or less sediment of the kind, 

A very serious disease among adult rainbow trout shows the follow- 
ing symptoms: The afflicted fish refuse to take food, and very dark 
spots, from ^ to 1 inch in diameter, appear on different parts of the body, 
varying in number from two or three up to twenty or thirty on each 
fish affected, a light spot about the size of a green pea appearing on 
the head immediately over the brain. The fish become restless and 
seek the shallow water i:i the corners of the pond, hiding among the 
plants, and begin to die within twenty four hours from the time the dis- 
ease is noticeable. They jump and dart around in the water in a 
frightened manner, settling back on their tails and sinking to the 
bottom of the pond iu their last struggles. This disease made its 
appearance at Wytheville in December, 1895; it was first observed 
among a lot of 637 yearling Von Behr or brown trout that had been 
delivered at the station on November 29. The first sign of the disease 
was noted about the 5th of December, and by the 12th of the month 
455 of the 637 fish were dead. 

These fish were in the nursery during the first stages of the dis- 
ease. The water in which they were held passed from them through an 
emi)ty pond into a second one containing about 1,000 large rainbow 
trout that had recently been stripped of their spawn. On the morning 
of December 23 the disease made its appearance among the latter, and 
by 4 o'clock in the afternoon of the same day 56 of them had died. 
Salt was applied and the water in the pond was drawn down to about 
300 gallons, and 150 pounds of common salt were sprinkled evenly 
through it. The fish Avere allowed to remain in this brine about 15 
minutes, when they showed signs of weakening by turning on their 
sides ; then fresh water was turned on freely. Good results were at 
once noticeable, the fish became quiet and appeared to rest more easily, 
and steadily improved, another application not being necessary. The 
final result was that 70 per cent of the adult rainbow trout that had 
been treated with salt were saved, while of the yearling brown trout 
that were not thus treated nearly 71i per cent died. 

Foul ponds cause disease, and if the fish become sick from this reason, 
they must be removed to a clean pond at once and given a salt-and- 
clay bath, which is applied as follows: While the salt bath, before 
described, is being given, 2 or 3 bushels of clay are placed iu the 
reservoir or supply-trough, and when the fresh water is turned on after 
salting, the reservoir is flushed for 30 minutes with roily water from the 
clay, and after the latter is washed away an increased amount of fresh 
water is turned on for ten days or more. 



Fish Manual. (To i 



'?>k 



Fish Manual. (To face page 78.) 



Plate 25. 



Note 

Rearing Ponds, Nos. 1 to i2 

Spawning „ .. 13 to 21 

December 18 9 9 



Scale 




PLAN OF STATION AT SPEARFISH, SOUTH DAKOTA, SHOWING TYPical ARRANGE 



MENT OF TROUT PONDS. 




MANUAL OF FISH-CULTURE. 79 

Adult fish are very liable to be affected with fungus, which generally 
appears after a bruise or hurt, or w lien the fish are in an emaciated 
condition. If the trouble results from an injury, it can often be cured 
before it spreads to the sound flesh, but if fungus spreads like a slimy 
web all over the fish, it is fatal. Fish must be handled very carefully 
daring the spawning season to prevent scarifying the body in any way, 
as they are especially susceptible to fungus at that period. Should it 
occur, the fish must be caught at once, rubbed with salt on the affected 
part, and then released in a pond or tank by itself, where it can be 
caught for further treatment in a day or two, while those affected all 
over the body should be killed and thrown out at once. 

"Glassy eggs" may be the result of overretention of the eggs on the 
part of the parent fish. If the eggs are not delivered within a reason- 
able length of time, say from 3G to 48 hours after they fall from the 
ovaries into the abdomen, they are surrounded with a thin watery fluid, 
having a glassy appearance, which if allowed to come in contact with 
water will change to a milky white, and the eggs absorbing this fluid 
become hard and " glassy," after which fecundation is impossible. 
Many thousand eggs have been lost annually on this account, and many 
brood fish lost or rendered worthless from the same cause. The fish in 
captivity will not spawn of their own accord unless they have access 
to gravel or earth in which to make nests. If attention is not given to 
the spawning fish and their eggs taken when ripe, they soon become 
very dark in color, the abdomen swells, and sometimes the head will 
enlarge, causing the eyes to i)rotrude. Under these conditions the fish 
will die in a few days, but with free and easy access to the raceway 
they will not often be thus affected. 



THE BROOK TROUT. 



DESCRIPTION OF THE FISH. 

The brook trout or sjfeckled trout (Sahelinus fontinalis) is one of the 
most beautiful, active, and widely distributed of the Americau trouts. 
It prefers clear, cold, rapid streams, and belongs to that group of trout 
known as charrs, characterized by the presence of round crimson spots 
on the sides of the body. Other members of this class are the saibling 
or charr {S. alpinus) of Europe and Greenland; the Sunapee trout {8. 
alpinns aureolus), found in parts of >Tew Hampshire and Maine; the 
blueback trout (*S^. oqnassa) of the Rangeley Lakes in Maine, and Dolly 
Varden trout, red-spotted trout, or bull trout (*S'. malma) of the Pacific 
States and Alaska. The lake trout also belongs in this group. 

The general form of the brook trout's body varies considerably, some- 
times being elongated and sometimes rather short, but the usual depth 
is about one-fourth or one-fifth of the length. The head is large and 
blunt, and is contained 4^ times in the body length. The large terminal 
mouth is i)rovided with teeth on the jaws, tongue, and palate bones, and 
also with a small patch on the vomer. The eye is placed high in the head ; 
its diameter is about one-sixth the length of head. The gillrakers on 
the first arch number about 17, of which 11 are on the lower arm. The 
scales are very small and numerous; about 230 are in the lengthwise 
series, and 35 above and 35 below the b,teral line. The dorsal and 
anal rays are 10 and 9, respectively. The tail is square or slightly 
lunate in the adult, forked in the young. 

There is considerable variation in the color of this trout, dependent 
on local conditions, sex, and age. The head, back, and sides of the body, 
dorsal and caudal fins are of a grayish or greenish color ; the back, head, 
dorsal, and base of caudal are mottled with dark green or black. In 
the male there is a reddish band along side of belly. Along 1 he middle 
of the side are numerous round light-red spots surrounded by whitish 
or light-brownish circular areas. The lower fins are dusky, with a pale 
or cream -color anterior border biiuided by a black streak; rem:iinder 
of fin often red in breeding males. The brook trout may be distin- 
guished from the other charrs by the dark -brown or black marblings on 
the back and the general absence of spots on the back. 

The i)arr-mark8, which are always [)resent in young tionts and sal- 
mons, are often found in large brook trout, and may even be permanent 
in aiiuarium or pond specimens and in wild fish with a restrit-ted environ- 
ment. These marks, which in the brook trout are about 8 in number, 
are large, dark, ^'erti(•al blotches or bars extending along the sides. 
Persisting parr-marks are shown in the accompanying colored illu><tra- 
tion of an artificially hatched and reared brook trout. (See frontispiece.) 
80 



Fish Manual. (To face page 



Plate 26. 




MAXUAL OF FISH-CL'LTUKE. 81 

FOOD, 8IZE, ETC. 

The brook trout has a voracious appetite aud takes aclvautage of 
eveiy opportunity to satisfy it except in the spawning season, when it 
takes no food at all. It is strictly a carnivorous fish, its food consisting 
chieiiy of Crustacea, niollusca, and various forms of Insects aud worms. 
When i^ressed with hunger it does not hesitate to devour its own kind. 

The size of these fish varies in different localities, usually in propor- 
tion to the abundance of natural food aud to the size of the body of 
water in which they are found. They seldom, however, exceed 2 pounds. 
The Au Sable Elver trout will rarely run as large as 2i to 3 pounds, but 
in other rivers of Michigan larger examples are occasionally found. In 
southern Xew York they seldom weigh over 2 pounds, while in the 
Eangeley Lakes, of Maine, they have been caught weighing 10 pounds. 
The rate of growth also varies with the surrounding conditions aud is 
more rapid in water of higher temperature and with a plentiful supply 
of food. Under favorable circumstances an average growth for the 
first year is from f to 1 ounce, in two years 8 to 10 ounces, in three years 
about 1 j)ound. 

While not of any considerable commercial importance, the brook 
trout is highly esteemed as a table delicacy on account of the flavor 
aud quality of its flesh, and, as it is very game, it is much sought after 
by sportsmen. Those from clear, swiftly flowing streams do ngt grow 
so large as those found in quiet and deeper waters, but are suxierior iu 
quality and appearance. 

RANGE, SPAWNING, ETC. 

The natural range of the broQk trout in the United States is from 
Maine to Georgia and westward through the Great Lakes region to 
Minnesota, and iu Canada from Labrador to the Saskatchewan. Owing 
to its hardy nature and ability to adapt itself to new surroundings, it 
may be successfully transplanted into suitable streams, and has been 
extensively introduced into waters to which it was not native, iu Mich- 
igan, Wisconsin, and ^Minnesota, many of the waters of the Eocky 
Mountains and the Pacific Coast, the Eastern States, and the creeks 
and rivers of the Alleghany range of mountains. With the possible 
exceptions of the rainbow trout and steelhead it is the hardiest mem- 
ber of the salmon family and will make a brave struggle for existence 
even with adverse surroundings. All streams can not be successfully 
stocked with this species ; the temperature of the water must not be too 
high nor the flow too sluggish, although an unfavorable temperature is 
no serious obstacle if the speed of the current is great enough to insure 
a sufficient aeration of the water, or if there are creeks fed by springs 
flowing into the main stream to which the fish can run. The best 
streams are those with a gravelly bottom, clear shallow water, and a 
steady current, and waters to be stocked must contain a sufficient 
amount of natural food and suitable places for spawning. 

F. M. 6 



82 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

The Michigan streams exemplify the i^ractical results attained in 
the introduction of brook trout in new waters. The Au Sable Eiver 
was long thonght to be especially adapted for this species, but it 
abounded with grayling, and until this beautiful fish began to disapjiear 
no movement was made toward introducing the brook trout. The 
lumber interests of that section made it necessary to use the river for 
C(mveyiug logs to various i^oints downstream, and, as the log-driving 
could be done only during the spring freshets, it came just at the time 
when the grayling were on their spawning-beds. They were driven 
away and the beds destroyed by the plowing of logs through the 
river bottom each year, till the fish gradually began to disappear. 
The brook Iroiit was suggested as the proper -substitute, because its 
spawning season is in the autumn when the river is undisturbed, and 
the Michigan Fish Commission began the work by planting 20,000 fry 
in the year 1SS5. Though additional plants were made from time to 
time, both by the Michigan and United States Commissions, no results 
were observed for some years, and it was thought that the work had 
been a failure. But the natural instinct of tlie fish had caused them 
to push from the main river into the small tributaries, where they 
multiplied and grew during these years till they finally crowded down 
into the river itself. Here they found as suitable a home as in the 
small streams, and their numbers gradually increased till now the 
stream' is completely stocked. 

In the autumn of 1895 a camp was established for the United States 
Fish Commission miles below the village of Grayling for the puri)ose 
of taking spawn from wild fish. The work was confined to rod-and-line 
fishing until the spawning season opened, when it was found necessary 
to adopt some other plan, as at this time the trout refuse to feed. 
During the five weeks, in which the rod was used exclusively, 3,000 
spawning fish were taken. A snmll seine was then used for capturing 
the fish, by hauling it at right angles to the current of the river, directly 
across the spawning-beds, which thickly dotted the river bottom in 
some places. By this method a tubful of trout at one haul was often 
talien, and during the period the fish were running between 8,000 
and 10,000 were obtained. This illustrates the abundance in which 
this species is found in a river to which it has been transplanted. A 
conservative estimate would place the number of trout taken from 
this stream in the season of 1895 at 100,000, perhaps 25 per cent being 
rainbow trout. Other waters of the State have been successfully 
stocked, so that the northern half of lower Micliigan now contains a 
network of trout streams, made by introducing this fish into waters 
where it was not indigenous. 

In its native haunts, whether in lake or stream, the brook trout is 
usually found in the same clear, cold, si)ring water, and prefers brooks 
or streams fiowing swiftlj^ over gravelly bottoms. It jiushes from the 
rivers into the small streams, seeking the headwaters, searching out 



MANUAL OF FISH-CULTURE. 83 

deep pools and eddies where it can lie concealed beneath the shelter of 
grassy banks or logs, and see withont being seen. Under artificial con- 
ditions it endures greater temperature than in its native waters, where 
it is seldom found in water over GO^ to 65°. It thrives at much higher 
temperature in swift, well-aerated streams than in sluggish waters. 

The brook trout spawns in autumn during the falling of the water 
temperature. The season, which usually lasts about two months, begins 
earlier in northern latitudes, in the Lake Superior region in September 
or even August, while in New York, New England, and lower Michigan 
it commences about the middle of October. 

As the spawning time api)roaches the fish push up toward the shal- 
lower waters where the female selects a spot near the bank of the stream 
and prepares her nest by washing out the sand with her tail and pushing 
aside the gravel with her nose. After forming a slightly concave depres- 
sion she deposits a part of her eggs on the newly cleansed gravel, and 
the male — which up to this time has been playfully swimming around 
the nest — emits milt upon them almost simultaneously. The female 
then covers the eggs with loose gravel. The spawning, impregnating, 
and covering are repeated continuously until the eggs are all laid. 
After the spawning-ground is once selected it is hard to drive the fish 
away, the female especially returning to the same spot at the earliest 
opportunity. A female has been taken from her nest and marked and 
then returned to the water a mile down the stream, and the next morn- 
ing was again found on the same bed. 

The eggs vary in size, but are usually one-sixth of an inch in diameter. 
The number yielded by one fish depends on its size and age, yearlings 
usually producing from 150 to U50, two-year-olds 350 to 500, and older 
fish 500 to 2,500. The time necessary for developing the eggs is depend- 
ent on the temperature of the water, varying from about 125 days in 
water at 37° F. to about 50 days in water at 50° F. 

TROUT-CULTURE IN AMERICA. 

The first attempt at artificial trout-culture in America was made in 
Ohio in 1853 with marked success. Further satisfactory trials were 
made in 1855 and 1859 in Connecticut and New York, and in 1864 a 
hatchery was established in New York which carried on the work on a 
large scale. Somewhat later the work was taken up by the State and 
United States governments and is now very extensively conducted in all 
parts of the country. The methods described in the following pages are 
those which have been found advantageous at the Northville Station 
and are there pursued. 

SPAWN-TAKING. 

Eggs are obtained from brood-fish held in ponds and from wild fish 
obtained at a field station located on a tributar}- of the Au Sable 
Kiver near its junction with the river. As the spawning season 
approaches, the brood-fish at the station are sorted according to age 
and size and transferred to spawning-ponds, which are seined once a 



84 REPORT OP COMMISSIONER OF FISH AND FISHERIES. 

week for ripe fish iu the early i)art of tlie season and later on three 
or four times a week. Great care is used in manipulating- the seine, 
and when its ends are drawn up on the bank the fish are transferred 
with dip nets from the bag of the seine into tubs, care being taken not to 
overcrowd the tubs. The fish are then examined; those which are not 
ready are returned to the pond, while the ripe males and females are 
placed in separate tubs or buckets. A good spawn-taker can tell at a 
glance if a female is ripe, and only in such condition should an attempt 
be made to take her eggs. As soon as these fish have been stripped 
and the eggs fertilized, the spent fish are liberated in a separate pond 
to avoid rehandling ttiem during the season. 

After the males and females are separated, an ordinary milk-pan 
coated with asphaltum paint on the inside, to prevent rust, is dipped 
in water and allowed to drain, leaving only the water that clings to the 
inside. Taking a female from the tub, the spawn-taker holds her as 
quietly as possible till all struggles cease, and then pressing gently 
with the thumb and forefinger a little above the ventral fins, passes his 
hand down the belly to the oviduct, repeating the operation till all the 
eggs are extruded. The eggs are immediately impregnated with milt, 
obtained from the male in a similar manner, except that more force is 
necessary and the pressure is made at a point about midway between 
the ventral and anal fins. 

The contents of tlie pan are next lightly stirred with a feather to 
insure impregnation of all the eggs possible. They now jjresent a 
milky appearance and are washed in as many changes of water as is 
necessary to thoroughly cleanse them from milt and refuse, when the 
pan, half-filled with fresh water, is placed in running water to keep 
the eggs at a low temperature. In 30 to 60 minutes, according to the 
temperature of the water, the separation of the eggs ensues, 

THE HATCHING APPARATUS. 

The apparatus at North ville is arranged as follows: A tank 15 feet 
long, with a partition running its entire length, is so placed that its 
lower end rests upon the upper end of a similar one 13 feet long, which 
differs from the upper one only in that it contains two boxes less. Nine 
partitions, placed crosswise of the tank, form, with the lengthwise 
partitions, a double row of eight compartments, each of which is 19^ 
inches long and 15i inches wide, and is provided with a waste-water 
channel or sluiceway leading into the next compartment. In these 
compartments are placed Clark hatching-boxes. 

The Clark box is 18 inches long, 14 inches wide, and 9i inches deep, 
and is made from |-inch dressed whitewood lumber. On its under side 
the box is provided with feet, 1 J inches square and § inch thick, to allow 
a free circulation of water under it and to prevent it from resting upon 
any sediment or refuse that may be deposited on the bottom of the 
tank; and on the inside in each bottom corner is fastened a block, f inch 
thick by li inches square, to support the trays. Five circular openings, 
I inch in diameter, jjermit the escape of water from the box. A slot is 



Fish Manual. (To face page 84.) 



Plate 27. 




MANUAL OF FISH-CULTURE. 85 

cut in one end of the box so that water from the compartment above 
can not flow into tbe one below without falbug into and passing through 
this box. Upon the feet or risers iuside the box rest 9 trays, placed 
one upon the other, the end of the box which, coutaius the slot flttiug 
snugly against the upper end of the compartment, in which is fitted a 
tin overflow. The whole is held in place by a crossbar or binder, which 
fits in f-incli grooves cut in both sides of the tank. Tlie binder, resting 
on the box, keeps it from rising in tlie' water, and is provided with feet 
so placed as to prevent the trays from floating in the box itself. The 
trays are perforated zinc or fine wire netting, tacked on a frame 16 
inches long and 7 inches wide inside measurement, made from finch 
pine 1^ inches wide. 

CARE OF THE EGGS. 

The eggs after separatiug are placed in troughs, the bottoms of which 
are covered with half an inch of gravel, and here they remain till the 
eye-spots begin to ai)pear.* During this interval of about 30 days the 
principal care consists in sorting out bad eggs, and, with a feather, 
gently changing the position of good ones to ))reveut sediment from 
collecting on them. At the expiration of this period they are ready for 
transfer to the hatching-boxes. They are drawn oft' the gravel by means 
of a siphon into a tub or bucket which has been half filled with water 
to preserve them from injury and then carefully dipped into a glass 
graduate, measured, and placed on the hatching-trays. The trays are 
arranged in the boxes in stacks of nine, and 5,000 eggs are allowed to 
each tray except the top one, which is left empty and serves only as a 
cover. The eggs from domesticated brook trout measure 350 to 450 per 
fluid ounce, depending on the age of the fish. Eggs from wild trout 
collected in the Au Sable Eiver measure 450 to the fluid ounce. 

At intervals of from 3 to C days during the period of incubation, in 
order to remove the bad eggs, the trays are taken from the boxes and 
placed in a shallow picking-trough through which a stream of not more 
than 3 gallons per minute is flowing. This trough is only wide enough 
to allow perfect freedom in handling the trays when i)utting them into 
or removing them from it, and only of suflicient depth to allow the eggs 
to be fairly covered. Nailed to the bottom on each side is a .1-inch strip, 
1^ inches wide, and running the entire length of the trough. These 
strips permit the free passage of water beneath the trays, as otherwise 
the water would flow over the tops and a great many eggs would be 
lost. The bad eggs are removed with tweezers, the labor being usually 
performed by girls, who become so expert that one girl will often remove 
100 bad eggs per minute. 

After the incubation has reached a stage where the fish are begin- 
ning to break their shells, the hatching-box is taken out and reversed, 

* The practice of boldiiiiif the new eggs on gravel until the eye-spots begin to 
appear is pursued at Northville with eminent success, but at the other trout hatch- 
eries of the CoumiissioD, where equally good results are obtained, it is customary 
to transfer the eggs to the hatching-trays as soon as they are impregnated, as is 
described in the chapter on the rainbow trout. 



86 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

the open eud being fixed snugly against the lower wall of the compart- 
ment. The closed end of the box being thus placed upstream, the 
water is prevented from entering except through its former exit, the 
holes in the bottom of the box, and is thus forced up through the box, 
with an exit at the top which prevents the sacs of the hatching fish 
from being forced, by pressure from above, down through the screen, 
as would be the case if the box were left in its former position. 

When the process of hatching is nearly completed the trays are 
removed and emptied into a large pan filled with water, where the dead 
shells and other refuse, being of low specific gravity, rise to the top 
and can be easily poured off. This is called washing the fish. The fish 
are then replaced upon the trays and returned to'^the hatching-boxes, 
where they remain until the food-sac is nearly absorbed, a period of from 
25 to 40 days, according as the temperature varies from 50° to .'^S^ F. 

The young fry, deprived of their food supply by the absorption of 
this sac, must soon be placed where they can get their sustenance else- 
where. They may be planted in waters suitable to their nature, or 
reared for breeding or other purposes at the station. 

THE FIELD STATION. 

The egg-collecting station previously referred to is on a tributary 
of the Au Sable, flowing about 1,000 gallons per minute. A dam is 
thrown across the stream and 100 feet above is a screen to prevent the 
fish from escaping in that direction. The dam is simply constructed 
by banking up mud, sand, and turf, and has a frame sluiceway 3 feet 
long, 2 feet wide, and 2 feet deep. In the sluiceway is inserted a 
double screen of ^-incli mesh wire netting, two screens being necessary 
to keep the overflow clear and reduce as low as possible any loss of 
fish through this outlet. The inclosure accommodates about 10,000 
fish. Fish are obtained with rod and line, until they begin to run from 
the deep i)ools upon the spawning-grounds, when much better results 
are obtained with nets. With an ordinary seine at the approach of 
the spawning season, the fish can be taken in large numbers from their 
spawning-beds. As the season advances and too many fish are caught 
that have already spawned, operations are suspended. 

As soon as ripe fish are found among those caught on the spawning- 
beds, the inclosure is hauled with a seine and the fish are looked over 
twice a week until the eggs are taken. When the season is fairly open 
the spawn may be taken from most of the fish immediately after they are 
caught, thus obviating the difficulty of transferring tlieai from the point 
of capture to the inclosure, in some cases a distance of 3 or 4 miles. 

For holding the eggs two pairs of trouglis are placed on standards 
driven into the bed of the stream^ with a passage between them wide 
enough to admit a man. The water is received through two 1-inch 
orifices in a bulkhead about 9 feet long, situated at the head of these 
troughs and fed by a r<nighly constructed raceway leading from a small 
spring about rods distant on the hillside. The water from each of the 



Fish Manual. (To face page 86.) 



Plate 28. 




MANUAL OF FISH-CULTURE. 87 

opeiiiugs feeds two troughs, so placed that the lower end of the upper 
one rests upon the head of the other, thus creating a fall of nearly the 
height of the troughs. Each trough is 14 feet long, 5 inches deep, and 
consists of a double row of boxes, each box 17 inches long, 15 inches 
broad, apd 2 inches deep, giving a capacity of from 8,000 to 10,000 eggs. 

SHIPPING GREEN EGGS. 

Green eggs can be safely moved at any time up to and including the 
eighth day. They are shipped from the held station to the hatchery 
iu cubical boxes constructed from ^-iuch pine lumber, just large enough 
to admit, with a surrounding air space of i-inch, 19 canton-tlannel trays, 
18 inches square on the inside, the frames of which are made from 
^-inch square white pine. The eggs are siphoned from the gravel 
boxes, as described above, and, using a graduated dipper for the pur- 
pose of ascertaining approximately the number of eggs necessary to 
make them about two deep on the tray, the i^acker pours them upon 
the tlannel and spreads them as evenly as possible with a feather. 
The tray is then placed in the box and the operation repeated until 
eighteen trays are filled with eggs. The nineteenth, ov top tray, is 
usually left empty, but if the weather is very warm it is filled with fine 
ice. The cover is then fastened down, the box marked, and the eggs 
are ready for shipment to the hatchery. 

PLANTING THE FRY. 

In their natural state, as soon as the weight of the food-sac has 
diminished by absorption enough to permit their rising, the fish begin 
to take food, and by the time the sac is entirely gone they are probably 
taking it regularly. When very young fry are transferred to outside 
waters where there is natural food only, it should be done 8 or 10 days 
before the sac is entirely absorbed, for, if delayed till after the sac dis- 
appears, many will die before they become accustomed to finding food 
iu their new home. 

Brook-trout fry are usually transported in ordinary rouud-shouldered 
cans of 10 gallons capacity, the number of fish per can depending 
entirely upon the distance they are to be carried and the facilities for 
taking care of them en route, such as opportunities for changing the 
water, supplying fresh ice, etc. For a short trip of from 5 to 10 hours 
duration, between 4,000 and 5,000 are carried in each can, but where 
they are to be on the road from 1 to a days, it is hardly safe to attempt 
carrying more than 2,500. The Commission distributes fry by means of 
its cars, built especially for the purpose, in which either running water 
is kept upon them or fresh air introduced into the water to make it life- 
sustaining. Small shipments are made by a special messenger in a 
baggage car, the railway companies usually offering every available 
opportunity for changing water, etc. The fish, upon arrival at the rail- 
way point nearest their destination, are carried thence by wagon to the 
stream where they are to be planted, by distributing them in small lots 
in different places where there is shallow water and a good bottom. 



88 REPORT OF COMMISSIONER OF FISH AND FISHERIES 

REAEING AND FEEDING. 

If tlie fry are to be reared for breeding, one week before tbe food-sac 
is absorbed they are changed from tbe trays to a birge pan and removed 
to tbe rearing-trongbs. Gravel sbouhi not be used in these troughs, 
as tbe unconsumed food works down into it and, becoming fungussed 
there, causes a greater spread of disease and increases the bibor of 
caring for the fish. 

The time to begin feeding the fry is readily ascertained by trial. If 
they rise to minute particles of food thrown upon the water, they are 
then ready for regular feeding. The time and frequency of feeding 
young fish, the kind of food, and the manner of feeding them, are of tbe 
greatest importance. Liver gives better results than any artificial 
food, and its preparation is very simple. Beef livers are ground by a 
meat-chopper and then strained through a fine-meshed screen, a thick 
pudding being made by the addition of water. A small portion, only 
such an amount as the fish will readily eat at a tin;e, is spread upon 
the surface of the water with a feather, and they are fed as often as six 
or eight times per day until they become used to the new diet. As 
they grow older the quantity of food may be increased but the fish are 
fed less frequently. At this stage tbe young fish have such a preca- 
rious bold upon life that too much attention can not be given to their 
care. Not more than 20,000 can be held with success in a feeding or 
rearing trough, and a regular stated supply of water is kept flowing 
through to prevent disease, and the fish are properly thinned out in 
order to prevent loss by suftbcatiou when they increase in size. About 
30 gallons of water per minute are sufticient for 20,000 fry, though this 
quantity is increased as the fish grow stronger and are able to breast a 
beavier current. 

In the spring season, when the water begins to grow Avarm, the fish 
require more room than the feeding-troughs aflbrd, and it is then nec- 
essary to transfer them to ponds. The North ville rearing-ponds are 
5 feet by 20 feet, made from 2 inch pine boards and provided with a 
gravel bottom, A pond of this size accommodates from 10,000 to 20,000 
fry till the middle of the summer, when the number is reduced to as 
low as 5,000. It is advisable to place not more than 5,000 in the pond 
at first to avoid the labor of reducing the number offish at different 
times, and also because crowding into too small a space retards their 
growth. 

At first the fish require coaxing to induce them to eat, as the change 
to their new abode has frightened them, and a great deal of patience is 
necessary in their treatment. They are fed at regular intervals three 
times per day. As their appetites are poor for the first few days, the 
liver will fall to the bottom and foul the pond, if great care is not exer- 
cised, and three fourths of an hour is not too long for feeding 5,000 fry. 
The time occupied in feeding is diminished and the amount of food 
increased according to tbe Judgment of the fisb-culturist; but their 
appetites should never be completely satisfied. 



Fish Manual. (To face page 88.) 



Plate 29. 




REMOVING GREEN EGGS FROM SHIPPING-TRAYS. NORTHVILLE. 




PACKING EYED EGGS. NORTHVILLE. 



MANUAL OF FISH-CULTURE. 89 

By earlj^ winter tliey will have grown to a length of from 3 to 6 inches, 
necessitating a change to a larger pond. The Northville breeding- 
ponds are 20 by 75 feet, and are constructed in the same manner as 
the rearing-ponds. One of these larger ponds accommodates 10,000 
yearlings, 5,000 two-year-olds, and about 3,000 fish from three to five 
years old. By the time the fish are three years old and over, less care 
is required in the preparation of their food, as the liver may be given 
to them in pieces half an inch in diameter. 

PACKING EYED EGGS FOB SHIPMENT. 

Eyed eggs prepared for shipment in the following manner have been 
sent from Northville to all parts of the United States with practically 
no loss: The trays upon which the eggs are to be shipped are made 
from the same materials as those upon which green eggs are carried, 
but are usually uuich smaller. Fewer eggs are placed upon a given 
surface than is the case with green eggs. For example, 10 trays, 12 
inches by V2 inches, will carry 50,000 eggs; 8 trays, 10 inches by 10 
inches, 32,000 eggs; and 5 trays, 8 inches bj' 8 inches, 12,500 eggs; or 
5,000, 4,000, and 2,500 eggs per tray, respectively. 

The trays are allowed to stand in cold water till thoroughly soaked, 
and are then drained off and taken to the packing-room. After the dead 
eggs have been removed from a box, the trays are taken out. drained, 
and removed to the packing-room. A f inch wooden frame, made to fit 
the inside of the canton-flannel tray, is then inserted, the eggs are 
carefully brushed with a feather from the wire trays and spread as 
evenly as possible upon the flannel. The eggs have been previously 
measured at the time when they were removed from the gravel to the 
hatching-box, so the number to be placed upon each tray can be easily 
determined. After the eggs are spread upon the flannel, the inside 
wooden frame is taken out, leaving a f inch margin around the inside 
of the tray. A square of mosquito netting large enough to lap over on 
all sides of the tray is laid upon the eggs and tucked down firmly along 
the insid«*. Sphagnum moss is scattered to a depth of about ^ inch 
upon this netting. The moss is ju^epared by removing sticks and other 
foreign matter; it is soaked in water a short time and then run through 
a clothes- wringer. In spreading it upon the netting the moss is picked 
apart and made as light and fluffy as possible, to give the eggs plenty of 
oxygen. 

When the required number of flannel trays are packed they are 
placed one upon another and cleated together on all sides, with boards 
at the bottom and top. This crate is usually placed, if possible, where 
the temperature of the air is below freezing, so that the moss may be 
slightly frosted before the crate is put in the shipping-case. 

A case is made large enough to allow a 4-inch space above, below, 
and around all sides of the crate when it is placed in position. Its 
bottom is filled with fine shavings, 4 inches deep, and the crate placed 
upon them as nearly as i)ossible in the center of the case. Shavings 



90 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

are packed tightly around the crate, a few being thrown in and pounded 
down securely before more are added. This must be well done, as the 
shavings are the only means of preventing a change in the position of 
the crate. The toj) of the crate is then covered with closely jjacked 
shavings and the cover of the case screwed on. By means of rope or 
iron handles the case may now be moved about with ease, and is ready 
for shipment. 

REFRIGERATOR BOX FOR SHIPMENTS ABROAD. 

A double box is used for this purpose. The inside one is 2.^ inches 
larger on all sides than the crate of trays, and the outside one large 
enough to make a 5-inch space on all sides when the smaller box 
is placed within it. The trays of eggs are prepared as in ordinary 
shipments, and when crated are placed in the smaller box upon a frame 
which is constructed from a i-inch strip, 2^ inches wide, tacked at right 
angles to the inside and bottom of this box. In the chamber thus 
formed between the crate and the box is packed finely chopped ice, an 
exit for the water resulting from its melting being provided by a half 
dozen openings in the bottom of the box. This box is now packed 
according to the same plan as that followed with the shipments for a 
short distance. Where there is an opportunity, it is well to have the 
case unpacked en route and new ice added. 

Eggs have been sent in this manner to Englaud, jMexico, New Zea- 
land, Japan, and South America, 



PJa'08 



